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

### Instruction:
 Tim赢得了100美元的抽奖奖金。他把20%给了他的朋友。他自己留下了多少钱？


### Response:
 他给了20%的100美元 = 100*.2 = <<100*.2=20>>20美元。
所以他自己留下了100-20 = <<100-20=80>>80美元。