On day one, a store sold 90 books. On each of the next d days, the company sold 62 books. If the average daily sales of books over this time period (including day one) is 66 books, what is the value of d? Options: A) 5 B) 6 C) 7 D) 8 E) 9
90 + 62d = 66(d+1).   4d = 24.   d = 6.   The answer is 6.
<result>B</result>
On day one, a store sold 90 books. On each of the next d days, the company sold 62 books. If the average daily sales of books over this time period (including day one) is 66 books, what is the value of d?