The equation d = 22.5n + 27.5 represents the amount of money, in dollars, that Kathryn earns for each sale she makes. The variable n represents the number of items sold, and the variable d represents the total amount of money earned.
What is the number of items Kathryn must sell in order to earn $500?
(A)10
(B)17
(C)21
(D)23