Imagine a question and stream-of-consciousness explanation for which this is the answer: 30
Question: Mary wants to bake 10 apple pies for a charity event. Each pie needs 8 apples and she already harvested 50 apples from the trees in her garden. How many more apples does she need to buy to make all 10 pies?
Stream-of-consciousness: She needs 10 * 8 = 80 apples to make the pies. So she has to buy 80 - 50 = 30 more apples.