human
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?
assistant
How many apples does each pie need? ** She needs 10*8=<<10*8=80>>80 apples to make the pies
How many more apples does Mary need to buy? ** So she has to buy 80-50=<<80-50=30>>30 more apples
#### 30