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

### Instruction:
 肯能一次可以做20个仰卧起坐。内森可以做肯的两倍，鲍勃可以做肯和内森总和的一半。鲍勃比肯多能做多少个仰卧起坐？


### Response:
 内森可以做2 * 20个仰卧起坐 = <<2*20=40>>40个仰卧起坐。
肯和内森总共可以做20个仰卧起坐 + 40个仰卧起坐 = <<20+40=60>>60个仰卧起坐。
鲍勃可以做60个仰卧起坐 / 2 = <<60/2=30>>30个仰卧起坐。
鲍勃比肯多能做10个仰卧起坐。