I really don't understand problem 1, could someone explain?? Why isn't it 0?

I'm going to assume you mean problem 1 in "let's practice" rather than the 1st problem in the video or just below the video. Problem 1 in practice is: (3/2)y-3+(5/3)z given the values of y=4 and z=3 Substitute the vales for the variables: (3/2)(4/1)-3+(5/3)(3/1) Follow PEMDAS rules. Multiply first. (3/2)(4/1)=12/2=6 (5/3)(3/1)=15/3=5 So, the expression is now: 6-3+5 Now, add and subtract from left to right. 6-3+5 = 3+5 = 8 The answer is 8. Why do you think it should be 0? Hope this helps.

Why is the answer to the second question 11? If I follow the order of operations shouldn't the answer be 5? Do addition first.. so 5 + 3 = 8.. then subtraction 13 - 8 = 5..

You aren't quite following order of operations. In PEMDAS, there are 4 steps, not 6. P = Parentheses: Do any work inside first E = Exponents: Do any exponents or radicals next MD = Multiply & Divide: These are one step. You need to work them from left to right AS = Add & Subtract: These are one step. Again, you need to work them from left to right So, when applied to the 2nd problem: 13-5+3 You go left to right: 13-5=8 Then 8+3=11 Hope this helps.

Wait, so, the first practice question has 3 over 2, isn't that an improper fraction? Am I supposed to treat it as an improper fraction and divide 3 into 2? Or, do I treat it as a normal fraction and try and figure out the problem? When I try to divide 3 into 2, i get 0.666... and so on. Thanks!

It's good that you saw that the answer 0.666... does not make good sense for the improper fraction 3 over 2. This should tell you that dividing 3 into 2 is an incorrect method. The fraction 3 over 2 actually means dividing 2 into 3. You should get 1.5 for the fraction 3 over 2. In general, the fraction a over b means dividing b *into* a, or equivalently dividing a *by* b. Have a blessed, wonderful day!

on the last step why was he able to eliminate posative 3 and negative 3? so quick without going through pemdas i know it will come out to 8 either way but did you use a faster way to get the answer? = 3 + 8 - 3

It's a faster way: 3 + 8 + (-3). Commutative Property: 3 + (-3) + 8. 3-3 = 0. 0 + 8 = 8. Or you can just mental math it and cancel out the 3 without rearranging the equation.

I dont understand problem 2. To be more specific I dont understand the fraction part 6(1/2). Could someone please help me.

Hey! To put it simply you just have to divide 6 by 2 to cut it in half in 13 - 0.5w + 6x when w =10 and x = 1/2. That makes the expression 13 - 5 + 3 = 11 if you follow PEMDAS. Hope this helps! ^o^

I am a bit stuck. how do we do 3/2 • 4 and 5/3 • 3 ? Please help!

Several ways to do it, 3/2*4/1=3*4/2=12/2=6 or 3*4/2=3*2=6.

How does one divide when one has 4(.5)

I'm not quite sure I understand your question. Can you please rephrase it?

the answer. i need it. It won't let me type in fraction

When typing fractions onto spaces when inputting answers's questions, try using the "slash" symbol, /,or the fraction command inside the pop-out menu.

Main content

Algebra 1

Course: Algebra 1 > Unit 1

Lesson 3: Substitution and evaluating expressions

Evaluating expressions with two variables: fractions & decimals

CCSS.Math:

6.EE.A.2

6.EE.A.2c

Google Classroom

We've already evaluated expressions with two variables. Now it's time to do it with fractions and decimals.

Khan Academy video wrapper

Evaluating expressions with two variables: fractions & decimalsSee video transcript

Let's study another example.

Evaluate start fraction, 1, divided by, 3, end fraction, a, minus, 1, minus, start fraction, 1, divided by, 2, end fraction, b when a, equals, 12 and b, equals, 6.

\begin{aligned} &\phantom{=}\dfrac13\blueD a-1-\dfrac12\goldD b \\\\ &= \dfrac13 \cdot \blueD {12}-1-\dfrac12 \cdot \goldD 6~~~~~~~~\text{Replace }\blueD{a} \text{ with } \blueD{12}\text{ and } \goldD b \text{ with } \goldD 6\text{.} \\\\ &=4 - 1 - 3 \\\\ &=0 \end{aligned}

Now, let's practice

Problem 1

Current

Evaluate start fraction, 3, divided by, 2, end fraction, y, minus, 3, plus, start fraction, 5, divided by, 3, end fraction, z when y, equals, 4 and z, equals, 3.

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Phong
Posted 4 years ago. Direct link to Phong's post “I really don't understand...”
I really don't understand problem 1, could someone explain??
Why isn't it 0?
Button navigates to signup pageComment on Phong's post “I really don't understand...”
(14 votes)
Answer
- Kim Seidel
  Posted 4 years ago. Direct link to Kim Seidel's post “I'm going to assume you m...”
  I'm going to assume you mean problem 1 in "let's practice" rather than the 1st problem in the video or just below the video.
  
  Problem 1 in practice is: (3/2)y-3+(5/3)z given the values of y=4 and z=3
  Substitute the vales for the variables:
  (3/2)(4/1)-3+(5/3)(3/1)
  Follow PEMDAS rules. Multiply first.
  (3/2)(4/1)=12/2=6
  (5/3)(3/1)=15/3=5
  So, the expression is now: 6-3+5
  Now, add and subtract from left to right.
  6-3+5 = 3+5 = 8
  
  The answer is 8. Why do you think it should be 0?
  Hope this helps.
  Comment on Kim Seidel's post “I'm going to assume you m...”
  (68 votes)
Steven C
Posted 3 years ago. Direct link to Steven C's post “Why is the answer to the ...”
Why is the answer to the second question 11? If I follow the order of operations shouldn't the answer be 5? Do addition first.. so 5 + 3 = 8.. then subtraction 13 - 8 = 5..
Button navigates to signup pageComment on Steven C's post “Why is the answer to the ...”
(9 votes)
Answer
- Kim Seidel
  Posted 3 years ago. Direct link to Kim Seidel's post “You aren't quite followin...”
  You aren't quite following order of operations. In PEMDAS, there are 4 steps, not 6.
  P = Parentheses: Do any work inside first
  E = Exponents: Do any exponents or radicals next
  MD = Multiply & Divide: These are one step. You need to work them from left to right
  AS = Add & Subtract: These are one step. Again, you need to work them from left to right
  So, when applied to the 2nd problem: 13-5+3
  You go left to right: 13-5=8
  Then 8+3=11
  
  Hope this helps.
  Comment on Kim Seidel's post “You aren't quite followin...”
  (52 votes)
Morgan Oesting
Posted 7 years ago. Direct link to Morgan Oesting's post “Wait, so, the first pract...”
Wait, so, the first practice question has 3 over 2, isn't that an improper fraction? Am I supposed to treat it as an improper fraction and divide 3 into 2? Or, do I treat it as a normal fraction and try and figure out the problem? When I try to divide 3 into 2, i get 0.666... and so on. Thanks!
Button navigates to signup pageComment on Morgan Oesting's post “Wait, so, the first pract...”
(6 votes)
Answer
- Ian Pulizzotto
  Posted 7 years ago. Direct link to Ian Pulizzotto's post “It's good that you saw th...”
  It's good that you saw that the answer 0.666... does not make good sense for the improper fraction 3 over 2. This should tell you that dividing 3 into 2 is an incorrect method.
  The fraction 3 over 2 actually means dividing 2 into 3. You should get 1.5 for the fraction 3 over 2.
  In general, the fraction a over b means dividing b into a, or equivalently dividing a by b.
  
  Have a blessed, wonderful day!
  Button navigates to signup page
  (7 votes)
Armani HATES MATH
Posted 4 years ago. Direct link to Armani HATES MATH's post “can somebody help me Eval...”
can somebody help me Evaluate 3/2 y - 3 +5/3 z when y=4 and z=3 like im just lost
Button navigates to signup pageComment on Armani HATES MATH's post “can somebody help me Eval...”
(6 votes)
Answer
- (Someone)
  Posted 3 months ago. Direct link to (Someone)'s post “hi, this is how you solve...”
  hi, this is how you solve it when y=4 and z=3
  3/2 y - 3+5/3z (substitute letters)
  3/2 times 4 - 3+5/3 times 3
  6 - 4-4+ 5/3 times 3
  6-4-4+5
  2-4+5
  -2+5
  3
  so, the answer is 3. hope this helps!
  Comment on (Someone)'s post “hi, this is how you solve...”
  (1 vote)
Leons Mathews
Posted 3 years ago. Direct link to Leons Mathews's post “I am a bit stuck. how do ...”
I am a bit stuck. how do we do 3/2 • 4 and 5/3 • 3
? Please help!
Button navigates to signup pageComment on Leons Mathews's post “I am a bit stuck. how do ...”
(4 votes)
Answer
- David Severin
  Posted 3 years ago. Direct link to David Severin's post “Several ways to do it, 3/...”
  Several ways to do it, 3/2*4/1=3*4/2=12/2=6 or 3*4/2=3*2=6.
  Button navigates to signup page
  (7 votes)
Guidance
Posted 2 years ago. Direct link to Guidance's post “How does one divide when ...”
How does one divide when one has 4(.5)
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(4 votes)
Answer
- Winter Soldier
  Posted 2 years ago. Direct link to Winter Soldier's post “I'm not quite sure I unde...”
  I'm not quite sure I understand your question. Can you please rephrase it?
  Comment on Winter Soldier's post “I'm not quite sure I unde...”
  (5 votes)
Juan Mendez
Posted 2 years ago. Direct link to Juan Mendez's post “on the last step why was ...”
on the last step why was he able to eliminate posative 3 and negative 3? so quick without going through pemdas i know it will come out to 8 either way but did you use a faster way to get the answer? = 3 + 8 - 3
Button navigates to signup pageButton navigates to signup page
(5 votes)
Answer
- Inspiron13
  Posted 2 years ago. Direct link to Inspiron13's post “It's a faster way: 3 + 8 ...”
  It's a faster way: 3 + 8 + (-3). Commutative Property:
  
  3 + (-3) + 8. 3-3 = 0. 0 + 8 = 8.
  
  Or you can just mental math it and cancel out the 3 without rearranging the equation.
  Button navigates to signup page
  (4 votes)
beborahim88
Posted 3 years ago. Direct link to beborahim88's post “I dont understand problem...”
I dont understand problem 2. To be more specific I dont understand the fraction part 6(1/2). Could someone please help me.
Button navigates to signup pageComment on beborahim88's post “I dont understand problem...”
(5 votes)
Answer
- Umamah Mahnoor
  Posted 2 years ago. Direct link to Umamah Mahnoor's post “Hey! To put it simply you...”
  Hey! To put it simply you just have to divide 6 by 2 to cut it in half in 13 - 0.5w + 6x when w =10 and x = 1/2. That makes the expression 13 - 5 + 3 = 11 if you follow PEMDAS.
  Hope this helps! ^o^
  Comment on Umamah Mahnoor's post “Hey! To put it simply you...”
  (4 votes)
landon.farrow
Posted 2 years ago. Direct link to landon.farrow's post “the answer. i need it. It...”
the answer. i need it. It won't let me type in fraction
Button navigates to signup pageComment on landon.farrow's post “the answer. i need it. It...”
(4 votes)
Answer
- Philip
  Posted 2 years ago. Direct link to Philip's post “When typing fractions ont...”
  When typing fractions onto spaces when inputting answers's questions, try using the "slash" symbol, /,or the fraction command inside the pop-out menu.
  Comment on Philip's post “When typing fractions ont...”
  (6 votes)
lisa.lecorchick
Posted 7 years ago. Direct link to lisa.lecorchick's post “evaluate (3/2)y - 3 + (5/...”
evaluate (3/2)y - 3 + (5/3)z when y = 4 and z = 3

how come we add 4(y) and 2 instead of multiplying
and
how come we cancel out the two 3s and keep the 5 instead of multiplying
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(1 vote)
Answer
- Blake Meloche (T1)
  Posted 2 months ago. Direct link to Blake Meloche (T1)'s post “you do multiply not add”
  you do multiply not add
  Comment on Blake Meloche (T1)'s post “you do multiply not add”
  (1 vote)