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

### Instruction:
 约翰买了3卷每卷20英尺的电线。制作一条项链需要4英尺的电线。他可以制作多少条项链？


### Response:
 每卷电线有20/4=<<20/4=5>>5条项链
所以他可以制作3*5=<<3*5=15>>15条项链