Assume that the sales of a certain appliance dealer can be approximated by a straight line. Suppose that sales were $9,000 in 1982 and $73,000 in 1987. Let $x = 0$ represent 1982. Find the equation giving yearly sales S.
A. $S = 12,800x + 9,000$
B. $S = 64,000x + 9,000$
C. $S = 12,800x + 73,000$
D. $S = 64,000x + 73,000$