conversations.from: human
conversations.value: A large puzzle costs $15. A small puzzle and a large puzzle together cost $23. How much would you pay for 1 large and 3 small puzzles?
conversations.from: assistant
conversations.value: A small puzzle costs $23 - $15 = $8.
  Three small puzzles cost $8 x 3 = $24.
  So, 1 large and 3 small puzzles cost $24 + $15 = $39.