Below is an instruction that describes a task. Write a response that appropriately completes the request in Chinese. Please answer in Chinese.

### Instruction:
 玛丽想为慈善活动烤10个苹果派。每个派需要8个苹果，她已经从自己花园的树上采摘了50个苹果。她还需要买多少个苹果才能做完所有的10个派？


### Response:
 10个派 × 8个苹果 = <<10*8=80>>80个苹果。
玛丽需要80 − 50 = <<80-50=30>>30个苹果。