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

### Instruction:
 詹姆斯为一群人做土豆。每个人吃1.5磅土豆。他为40个人做土豆。一袋20磅的土豆售价5美元。这要花多少钱？


### Response:
 40个人吃了40*1.5=<<40*1.5=60>>60磅的土豆
60磅的土豆售价为60/20*5=<<60/20*5=15>>15美元