On day one, a store sold 96 pens. On each of the next d days, the company sold 44 pens. If the average daily sales of pens over this time period (including day one) is 48 pens, what is the value of d? Choose the correct choice from the following answers:  A) 9  B) 10  C) 11  D) 12  E) 13

Rationale: 96 + 44 d = 48 ( d + 1 ) . 4 d = 48 . d = 12 . the answer is d .
Answer: D