conversations.from: human
conversations.value: John decides to fix a racecar.  It cost $20,000 to fix but he gets a 20% discount.  He wins his first race but only keeps 90% of the money.  The prize is $70,000.  How much money did he make from the car?
conversations.from: assistant
conversations.value: He gets a 20000*.2=$4000 discount
  So he paid 20000-4000=$16000
  He kept 70000*.9=$63000
  So he made 63,000-16,000=$47,000