A certain car dealership sells only Full-size and Mid-size c

A certain car dealership sells only Full-size and Mid-size cars. One of its sales representatives receives an annual salary of $15,000. He also receives a commission of $800 for each full size car he sells and $500 for each midsize car he sells. What is the least number of cars he must sell in a year to receive total annual earnings of exactly $25,000?

A) 7
B) 12
C) 13
D) 14
E) 17