conversations.from: human
conversations.value: Ben's new car cost twice as much as his old car. He sold his old car for $1800 and used that to pay off some of the cost of his new car. He still owes another $2000 on his new car. How much did his old car cost, in dollars?
  Find the solution.
conversations.from: assistant
conversations.value: His new car costs 1800+2000=3800 dollars.
  His old car cost 3800/2=1900 dollars.