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### Course: 3rd grade > Unit 8

Lesson 3: One and two-step word problems# Setting up 2-step word problems

Sal represents 2-step word problems with equations.

## Want to join the conversation?

- Why do we need parentheses?(6 votes)
- We use the parentheses to make it clear that we are
**dividing the entire result**of`58-13`

(number of pages remaining) by`5`

to figure out the number of days to finish the book.

Without it, the equation would look like`d = 58-13/5`

, which would only divide the`13`

(remember Order of Operations).

Hope this helped!(12 votes)

- How!!I don´t know how to do this can one of you guys help me??!!I don´t get a thing!!(2 votes)
- carefully watch the video!(3 votes)

- why do we have parentheses(0 votes)
- Hi oashish! We use parenthesis in math for many things. When you have a number in parenthesis next to another number, it means you have to multiply. If you have an expression in parenthesis, it means that you have to do that expression first in the overall equation. All in all, parenthesis are an essential part of math. Hope this helps. Have a great day! 😁(5 votes)

- Why do we need parentheses?(1 vote)
**Copying from the great answer from****TheReal3A***"We use the parentheses to make it clear that we are dividing the entire result of 58-13 (number of pages remaining) by 5 to figure out the number of days to finish the book.*"

Without it, the equation would look like d = 58-13/5, which would only divide the 13 (remember Order of Operations).*Hope this helps!*(1 vote)

- Why parenthesis I mean can't you just do the problem without parenthesis?(0 votes)
- Hello! I'm so happy you asked! So yes you could do the problem without the parenthesis, but it keeps the two equations apart so it makes it easier. What this also does is break it up into a few steps.(4 votes)

- who is this. I bet it is not Sal(0 votes)
- what are parenthesis for(0 votes)
**Parentheses**are () enclosing some part of an expression. They are**grouping symbols**, which*associate*numbers and operations together.

Also, the**Order of Operations**tells us to evaluate groupings first!

The video shows how you can find**number of days**to finish a book.

Well, you know there's`58`

pages in the book, and you have already read`13`

pages.

So the number of**remaining pages**is`58 - 13`

.

However, you can read`5`

**pages per day**(this is a rate). By dividing number of remaining pages by the rate, you get the**days left**.`(58 - 13)/5`

You have to put parentheses to**associate**all of`(58 - 13)`

with the number of remaining pages! Otherwise, it would look like`58 - 13/5`

, which would only divide the`13`

(incorrect).

Hope this helped!(4 votes)

- hello every one '-' press history crl and h at the same time and wach(0 votes)

## Video transcript

- [Instructor] My book is 58 pages. I have already read 13 pages. I plan to read five pages each day until I finish the book. Which equation could I use to find out how many days, d, it will take
to finish reading the book? So pause this video and see
if you can figure that out. Okay, so let's first think about the important
information they're giving us. They're giving us the number
of pages that are in the book. They're giving us how
much we've already read. We've already read 13 pages. And they also tell us
how much we plan to read. I plan to read five pages each day until the book is finished. And then we want an
equation that could use to find how many days. And d is how we're going to
represent the number of days, let me do it in the same color, it'll take to finish reading the book. All right, so if we knew how
many pages we have to read and we were divided by the fact that we're reading five pages per days, well, then that would give
us the number of days. So how many pages do we have
left to read in the book? Well, the book is 58 pages. We've already read 13, so we
could subtract out 13 of those. So this expression right over here, this is how many pages
we have left in the book. Let me write that down. How many pages left. And if we wanna figure out
how many days it's going to take to read these, we would divide this by how
many pages we read each day. And we see that we read
five pages each day. So if we divide this by five,
then this whole expression, let me do it in this color, this whole expression is going to tell us how many days left. How many days left. And so this is going to be equal to d 'cause d is the number of days left to finish reading the book. Now, if we look at these choices, that's exactly what we have
right over here in choice C. We can make sure that these
others don't make sense. 58 plus 13, no, that would be a situation where we're reading 13 pages more than the number of pages
that are in the book. That doesn't make sense. And that's happening for
both choice A and choice B. It would also not make
sense to multiply by five because it's not going to
take you five times more than the number of pages to read the book. You're going to divide by five. You're reading five pages every day. And we are done.