conversations.from: human
conversations.value: Agatha has some money to spend on a new bike. She spends $15 on the frame, and $25 on the front wheel. If she has $20 left to spend on a seat and handlebar tape, how much money, in dollars, did she have at first?
conversations.from: assistant
conversations.value: Agatha spends 15+25=40 dollars.
  Agatha had 40+20=60 dollars at first.