conversations.from: human
conversations.value: I need a clearer understanding of how to solve: John repairs 5 cars.  3 of the cars take 40 minutes each to repair.  The remaining ones take 50% longer each to repair.  He makes $20 per hour repairing cars.  How much money does he make?
conversations.from: assistant
conversations.value: The 3 cars take 3*40=120 minutes to make
  He repairs 5-3=2 more cars
  They each take 40*.5=20 minutes longer per car
  So they each take 40+20=60 minutes
  So he repaired cars for 120+2*60=240 minutes
  That is 240/60=4 hours
  So he made 4*20=$80