Question

You want to buy a car. You have $800 for a 20% down payment and need a loan for the remainder of the car's cost. You find a loan with 2.9% interest. How much would the sticker price of the car be?

Answer 1

This isn't a statistics question. The translation of the second sentence is

800 is 20% of what number
800 = 0.20x
800/0.20 = x
4000 = x
x = 4000

The sticker price of the car needs to be $4000 or less.

With the given information, the rate on the loan is irrelevant.