###Human: 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?, ### Assistant: Dubois has to pay $13,380 – $5,400 = $7,980 more.
He will pay that in $7,980 : $420 = 19 months. 
 So the answer is :  19