Sheryl paid a plumber x dollars per hour for a 6-hour job plus $70 for parts. The total charge was $325. Which equation can be used to determine how much the plumber charged per hour?

A. 6x - 70 = 325
B. 6x + 70 = 325
C. (70 + 6)x = 325
D. (70 - 6) x = 325