prompt: 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?
messages.content: 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?
messages.role: user
messages.content: 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
messages.role: assistant