She needs 10*8=<<10*8=80>>80 apples to make the pies

So she has to buy 80-50=<<80-50=30>>30 more apples

# Answer

30
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
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?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
30
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?
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