conversations.from: human
conversations.value: John decides to trade in his stereo system.  His old system cost 250 dollars and he got 80% of the value for it.  He then buys a system that costs $600 that he gets a 25% discount on.  How much money came out of his pocket?
  Solve it.
conversations.from: assistant
conversations.value: He got 250*.8=$200
  He gets a 600*.25=$150 discount on the second system
  So it cost 600-150=$450
  So he was 450-200=$250 out of pocket