conversations.from: human
conversations.value: Darryl is an inventor who just designed a new machine. He had to pay $3600 for the parts to construct the machine, and $4500 for the patent he applied for once he built it. If the machine sells for $180, how many machines does Darryl need to sell to break even after the costs?
conversations.from: assistant
conversations.value: Darryl paid 3600 + 4500 = $8100 in costs for the parts and patent.
  Thus, Darryl needs to sell 8100 / 180 = 45 machines to break even.