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Lesson 5: Evaluating expressions with multiple variables

# Evaluating expressions with two variables: fractions & decimals

Evaluating expressions with two variables involves substituting the given values for each variable and simplifying the expression. By practicing with examples, we can improve our skills in solving these types of problems, ultimately enhancing our understanding of algebraic expressions and their real-world applications.

## Want to join the conversation?

• at in the video he says if we get half of 7 we get 3.5 but how does he get the that?
• The decimal representation of 1/2 is 0.5, which is what he uses in the video.
He wrote 0.5 and says "one half", since they a representations of the same thing.
Hope that helped.
• How does this type of pb solving resolve real world dilemmas??
• There are many formulas used in the real world, perimeter, area, compounded interest, tax calculations, etc. Formulas use variables. If you want to use the formula, you need to know how to replace the variables with the appropriate values and do the math. The values given to the variables could be decimals, fractions, mixed numbers, etc. The formula could have a fraction or a decimal.
• Why does Sal halve 7 when he multiplies it by 0.5?
• because if you multiply anything by any value less than 1, it gets necessarily cut in half.
• Can someone help me? The video didn't help me and i am struggling.
• It's Basically substitution
• i dont understand how 12 (1/4) equals 3 can someone help
• 12 in fraction form is 12/1
Multiply 12/1 (1/4) = (12*1)/(1*4) = 12/4 = 3
Hope this helps.
• PEMDAS or GEMDAS always applies whenever you do something like this, right? I hope I'm right.
• Yes, the order of operations rules always apply in problems like these.
• When we say decimals isn't the decimals said as for example 0.45 said as 0 and 45 hundredths?
• You can say it that way. Or, you can just say: 45 hundredths.
• why do you have to make 0.25 a fraction?
• You don't. 8(0.25) = 2, so you get the same result in decimal form.
• how do you subtract first then add ? it doesnt make sense when you your using the P.E.M.D.A.S method . this website has the answer backwards . i got half my answers wrong cause you guys subtract then add which is the other way around
• PEMDAS has 4 rules / steps, not 6.
P = First, do any work inside parentheses or other grouping symbols.
E = Do exponents and radicals 2nd.
MD = Multiply and Divide are one rule/step. We work them from left to right.
AS = Add and Subtract are also one rule/step. We work them from left to right.

This is why the subtraction is being done before the addition in the video. The subtraction is on the left, so it comes first.

Hope this helps.