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

### Instruction:
Ken can do 20 sit-ups without stopping. Nathan can do twice as many, and Bob can do half the number of Ken and Nathan's combined sit-ups. How many more sit-ups can Bob do compared to Ken?

### Response:
 Nathan anaweza kufanya 2 * 20 = <<2*20=40>>40 push-up.
Idadi ya push-up ya Ken na Nathan ni 40 + 20 = <<40+20=60>>60 push-up.
Bob anaweza kufanya 60 / 2 = <<60/2=30>>30 push-up.
Bob anaweza kufanya push-up 30 - 20 = <<30-20=10>>10 zaidi kuliko Ken.