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

### Instruction:
 约翰去洗手间8次需要20分钟。去6次需要多长时间？


### Response:
 他每次花费20/8=<<20/8=2.5>>2.5分钟。
所以去6次需要2.5*6=<<2.5*6=15>>15分钟。