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

### Instruction:
A set of 7 spoons costs $21. If each spoon would be sold separately, how much would 5 spoons cost?

### Response:
A set of 7 spoons costs $21, so one spoon from the set costs 21 / 7 = $3.
So if sold separately, 5 spoons would cost 5 * 3 = $<<5*3=15>>15.
#### 15