prompt: Jack bought 3 books a month at $20 each.  He sells them back at the end of the year for $500.  How much money did he lose?
messages.content: Jack bought 3 books a month at $20 each.  He sells them back at the end of the year for $500.  How much money did he lose?
messages.role: user
messages.content: He bought 3*20=$<<3*20=60>>60 of books a month
  That means he bought 60*12=$<<60*12=720>>720 of books a year
  So he lost 720-500=$<<720-500=220>>220
  #### 220
messages.role: assistant