Victoria got 32 birthday presents for her birthday. She’s opened 7 of them. How many presents does she have left to open?
This is a subtraction problem because we want to find out how many presents she has left to open after she’s already opened some of her presents. We take the total number of presents she has, and then we subtract the number of presents that she’s opened.
The keywords to look out for in a problem involving subtraction are: take away; how many more; how many less; how many left; greater; smaller.