Cheque comun por que se debe tener en cuenta el monto escrito en letras y no en numeros??

Lydia finds a car that costs 13,000, and she has 2,500 saved for a down payment. if she qualifies for a 5% interest rate, how much will the interest be calculated on? 13,000? 12,000? 15,500? 10,500? in : )