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

### Instruction:
 黛安比塞西尔多买了二十个苹果。如果塞西尔买了十五个苹果，他们一共买了多少个苹果？


### Response:
 黛安买了15 + 20 = <<15+20=35>>35个苹果。
因此，他们一共买了15 + 35 = <<15+35=50>>50个苹果。