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

### Instruction:
 Jack orders 3 sandwiches that cost $5 each. He pays with a $20 bill. How much does he get in change?


### Response:
 费用是3 * $5 = $<<3*5=15>>15。
所以他得到了$20 - $15 = $<<20-15=5>>5的找零。