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

### Instruction:
 辛迪有37个信封。如果辛迪给她的5个朋友每人3个信封，她还剩下多少个信封？


### Response:
 辛迪给每个朋友3个信封 x 5个朋友 = <<3*5=15>>15个信封。
辛迪还剩下37个信封 - 15个信封 = <<37-15=22>>22个信封。