Ed earns a $100 commission on each computer he sells plus a base salary of $50,000 . His total income last year was 75,000 . Which equation can be used to find how many computers Ed sold last year ? A. 50,000 + 100x = 75,000 B. 50,000 - 100 x = 75,000 C. 75,000 + 100x = 50,000