13. At Hamburger Heaven, Corissa paid less than $15 for her order of x hamburgers and x bags of french fries. Each hamburger cost h dollars, and each bag of french fries cost f dollars. Which of the following expressions represents the amount of money, in dollars, that Corissa should have received back after she paid for her order with $15 ?

(Note: There is no tax on food at Hamburger Heaven.)