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

### Instruction:
It takes Derek 9 minutes to walk a mile if he doesn't have to walk with his brother. If he has to take his brother it takes 12 minutes to walk a mile. How many minutes longer would it take him to walk 20 miles if he had to take his brother?

### Response:
Alone it would take him 9*20=<<9*20=180>>180 minutes
With his brother, it would take him 12*20=<<12*20=240>>240 minutes
240-180=<<240-180=60>>60 more minutes
#### 60