To find out how many books Sarah can purchase with her saved money, we can set up the following equation based on the information provided:
Let \( b \) be the number of books Sarah can buy. Each book costs $15, and Sarah has $60 saved. The equation that represents this scenario is:
\[ 15b = 60 \]
This equation shows that the total cost of the books (15 dollars per book multiplied by the number of books) is equal to the amount of money Sarah has saved ($60).
To solve for \( b \): \[ b = \frac{60}{15} \] \[ b = 4 \]
So, Sarah can purchase 4 books.