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## Early math review

### Course: Early math review > Unit 5

Lesson 9: Word problems within 100- Adding and subtracting on number line word problems
- Adding two digit numbers on a number line
- Add and subtract on the number line word problems
- Subtraction word problem: tennis balls
- Addition word problem: horses
- Addition word problems within 100
- Subtraction word problem: snow
- Subtraction word problem: crayons
- Subtraction word problems within 100

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# Subtraction word problem: tennis balls

Sal solves a 2-step subtraction word problem with numbers less than 100.

## Want to join the conversation?

- Can you just add than subtract(8 votes)
- Yes you can add and than subtract. Adding 19 + 6 is the same as grouping all the balls that are no longer with the class into a single number. Then you can subtract that number from 45 and get the number of balls that remain.(2 votes)

- How can I tell if I am adding or subtracting?(0 votes)
- I think of it as money like this guy above me, when you put money in a bank, you are checking in, and when you are pulling money out your are withdrawling or taking a way.

example:

Jill has 100,000,000 dollars in her bank, and she adds 10,000,000, then she takes 5,675,000 away. how much does she have left?

HOPE IT HELPS!(1 vote)

- Is there a easyer way to math?? Because I'm not very good at math.(3 votes)
- allison.1473: Don't ever say you are not good at math! Math is about so much more then just solving equations, it's about seeing numbers in the world around you. As Bug Sanders said, it will take practice. But as you do more and more math you will find ways to do math that are easier for you. For now, just try to practice a lot, be open to new ideas and techniques, and keep on asking questions!(3 votes)

- Hi. Can someone help me with a question?(4 votes)
- Sure, I can help you with any questions you have. Whenever you want you can just ask me your question and I will answer it to the best of my ability.(2 votes)

- do you always start with the bigger number(2 votes)
- For now, the bigger number will always be the number that you subtract the smaller number from. Big - Small = Positive Difference. Later, you'll get introduced to what happens when you subtract a larger number from a smaller number, which leads you to a whole different class of numbers that are less than 0.(3 votes)

- How do you subtract a smaller number to a bigger number?(1 vote)
- The answer goes less than zero, and goes into the negatives, such as 5-7= -2, because it goes two spots below zero.(5 votes)

- I have problems when it comes to word problems. Can someone help me with this problem? This is the problem: Your class is holding a fundraiser for a local charity. After the first week, your class raised 1/8 of your goal. After the second week, your class raised a total of 3/5 of your goal. What fraction of the goal was raised during the second week of the fundraiser?

All answers are highly welcome. Thank you^^(2 votes)- I think I'm too late to answer this but I'll still show you the answer.

First you have to identify the given, which are the goal (1), the first week progress (1/8), and the total goal after the second week (3/5). Since the class finished 1/8 of the goal after the first week, and you know how many did the class raised after the second week (3/5), the equation to find the number is 1/8 + ? = 3/5 or 3/5 - 1/8 = ?. To find the answer, you need to find the LCD, which is 40, so that makes it 24/40 - 5/40 = ?. Subtract the nominators and the answer is 19/40.(3 votes)

- The question could probably have been a bit clearer when it says that 19 balls got thrown over the fence. When I first read that I immediately assumed that 19 balls got thrown from the outside, in; as opposed to from the inside, out. This was matter was cleared up when he specified this but from the text alone it could be read either way.(1 vote)
- There was a question in which I didn't knew if it was inclusive or not. I don't quite remember it but could be the fact English isn't my mother tongue. Either way, I think the text should be more declarative in order for international kids to answer correctly and not be frustrated too. Even English speaking kids may encounter problems, like you did.(4 votes)

- it's just regular subtracting why is tennis balls important they don't add anything except to the story and why does a teacher have tennis balls?(2 votes)
- He is okay at this stuff! But yet I never learn(2 votes)

## Video transcript

- Mrs. Grange's second grade
class has 45 tennis balls. Whenever I do a word problem like this I just like to write down the information that they're giving me. So we're gonna start with 45 tennis balls. They then tell us that 19 tennis balls, so she starts with 45 tennis
balls to play with at recess. They then tell us that 19 tennis balls get thrown over the fence and 6 tennis balls just disappear. How many tennis balls does
Mrs. Grange's class have left? So what I'd like to do, when I do these type of word
problems, let's say, okay, first of all where am I starting from? Well, I'm starting from 45 tennis balls and then whats happening? Am I gaining tennis balls
or am I losing tennis balls? Well I started with 45 or Mrs. Grange's class started with 45 then 19 tennis balls get
thrown over the fence so they're losing the balls. And then another 6 tennis balls disappear, so both of these are losing tennis balls. And since I'm losing something, since I'm losing the tennis balls, or some of the tennis
balls that I started with I should subtract here. Another clue that subtraction
might be interesting is because it says how many tennis balls does Mrs. Grange's class have
left, which implies that, well, she doesn't have
all the tennis balls that she started with so we're probably going to subtract some balls. But it comes straight
out of the word problem. 19 tennis balls get thrown
over the fence, she loses them, so we should subtract that
from the original amount. And then another 6 just
disappear, so we should then subtract that on top of
the 19, so let's do that. So let's first subtract the 19. So we start with 45 tennis balls, and then 19 balls get
thrown over the fence, so 19 get thrown over the fence
so we're subtracting them. They lose those balls, so
what is this going to be? Well if we look in the ones place we have 5 ones minus 9 ones. Well, since 5 is less than 9
we want to do some regrouping. So let's go to the tens place. Instead of 4 tens, lets
try that as 3 tens, and then take that 10 , turn it into ones so it's gonna be 10 ones. 10 ones plus 5 ones is 15. Now we're ready to subtract. 15 minus 9, well that's gonna
be 6 because 9 plus 6 is 15. And then 3 tens minus 1 ten
is going to be 2 tens, so 26. But are we done? No. This is just the number
of balls we have left after the 19 get thrown over the fence but before we count the
6 that just disappeared. So we also have to take away 6 for the 6 balls that disappeared. So let's do that. So after 19, so we started with 45, 19 get thrown over the fence,
we have 26 at that point. Then, 6 balls just disappear
so we have, once again they disappear, they're not,
you know, magically appearing. Since they're disappearing we subtract. So we, they're disappearing,
so we want to subtract those. So how many do we have left? Well, 6 ones minus 6 ones is 0 ones. 2 tens minus, well nothing here, that's just going to be 2 tens. So how many do we have left? Well, or how many does Mrs. Grange's second grade class have left? Well you see it right here. They have 20 tennis balls,
20 tennis balls left. Started with 45, 19 get
thrown over the fence so they lose them,
that's why we subtracted. That gets us to 26,
then 6 of them disappear so we take the 6 away
from the 26 to get to 20.