conversations.from: human
conversations.value: Amanda received $50 as a gift. She plans to buy two cassette tapes that cost $9 each and a headphone set that costs $25. How much money will she have left?
  Solve this problem.
conversations.from: assistant
conversations.value: Amanda spent 2 tapes * $9/tape + $25 = $43.
  Amanda has $50 - $43 = $7 left.