What is a ratio?
A ratio has two or more numbers that symbolize relation to each other. Ratios are used to compare the numbers, and you can compare them using division.
If the ratio is 2: 3, (children's section: chapter books) we can use this equation to figure out how many chapter books there are if there are 500 children's section books:
Why do we multiply by 1.5?
In the ratio 2: 3, 2 is being multiplied by 1.5 to get to 3. If the relationship between the numbers 2 and 500 stays proportional, we multiply 500 by 1.5.
Therefore, the ratio of children's books to chapter books is 500: 750, meaning there are 750 chapter books.