conversations.from: human
conversations.value: John buys 20 hours of music a month.  The average length of a song is 3 minutes.  He buys each song for $.50.  How much does he pay for music a year?
  Solve it.
conversations.from: assistant
conversations.value: He buys 20*60=1200 minutes of music a month
  So that is 1200/3=400 songs
  That means he pays 400*.5=$200 a month
  So it comes out to 200*12=$2400 a year