conversations.from: human
conversations.value: Mr. Dubois buys a new car for $13,380. He pays $5,400 and pays the rest by giving $420 a month. In how many months will the car be fully paid for?
  Give me a clear explanation.
conversations.from: assistant
conversations.value: Dubois has to pay $13,380 – $5,400 = $7,980 more.
  He will pay that in $7,980 : $420 = 19 months.