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

### Instruction:
 昨天，桑尼从他的朋友那里收到了45盒饼干。他给了他弟弟12盒，妹妹9盒，还给了他表弟7盒。他还剩下多少盒饼干？


### Response:
 桑尼总共给了12 + 9 + 7 = <<12+9+7=28>>28盒饼干。
因此，他还剩下45 - 28 = 17盒饼干。