The total cost of the car = down payment + total installments
For total installments:
The first step is to find out the number of months Tom will pay:
5.5 years x 12 months in a year = 66 months
If he pays 325 per month, he will pay 325 x 66 = 21,450 in installments.
Add this to his down payment for the total cost of the car:
3,800 + 21,450 = 25,250 (the total cost of the car)