Interpreting picture graphs (notebook) | Math | 3rd grade | Khan Academy

Maria has 70 pages in her notebook. She made a graph of the kinds of writing on all the pages she has used so far. How many pages are left in Maria's notebook?

So down here, we have a picture graph or pictograph showing all the pages Maria's used so far in her notebook. But we're asked how many pages are left in Maria's notebook. To find that out, we need to know how many she started with, which it tells us right here: her notebook started with 70 pages. Then, if we take away the ones she's used so far, if we take away however many pages she's used so far, that will tell us how many are left in her notebook.

So the question here is: how many has she used so far? Well, we don't know exactly, but we have this picture graph that will help us find that answer.

So, super important on the picture graph: first is right here. It tells us that each of these pieces of paper represents two pages in Maria's notebook. For poems, she wrote on two pages and another two pages, where she wrote a total of four pages about poems. She did reports on two, four, six, eight, ten pages.

She wrote stories. She wrote a lot of stories. She wrote stories on two, four, six, eight, ten, twelve, fourteen pages of stories. She wrote letters on two, four, six, eight pages. Finally, she journaled on two, four, six, eight, ten, twelve pages.

So this here, this is the total pages she's used so far. If we combine all of these—the 4 for poems and 10 for reports and so on—this will tell us how many pages she's used so far. Then we can substitute that in right here, and we can say 70 she started with, take away what she used so far, and we'll get our final solution for the pages left in her notebook.

So let's find this total. There's four pages for poems plus 10 pages for reports, 14 on stories, eight more pages to write letters, and 12 pages to journal. So if we add these: I'll start with the ones. Two ones plus eight ones is ten ones. Ten ones plus four ones is fourteen plus zero more is still fourteen ones. Plus four more is eighteen ones.

Plus now let's add our tens: one ten plus another ten is two tens or twenty, plus one more ten is three tens or thirty. So she's eighteen ones plus three tens. So eighteen plus thirty pages, which is a total of forty-eight pages she's used.

So far, if we take those 48 away from 70, we'll know how many pages are left. One way we could do this is we could think of it as counting up. We could say there's 48 pages used. Let's count up to 70 to see how many more pages there still are in the notebook. If we count up from 48 to 50, that's two more pages she has. Then from 50 to 70 is twenty. That's 20 more pages she has.

So she has a total of 22 more pages left in her notebook.