question: John rents his car out 10 times a month for 3 hours each time.  He gets paid $25 an hour.  If his car payment is $500, how much profit does he make on his car?
answer: He rents his car 10*3=<<10*3=30>>30 hour a month
  So he makes 25*30=$<<25*30=750>>750 a month
  That means he has a profit of 750-500=$<<750-500=250>>250 a month
  #### 250