A and B are two multiples of 14, and Q is the set of consecutive integers between A and B, inclusive. If Q contains 9 multiples of 14, how many multiples of 7 are there in Q? Choose the correct choice from the following:
A) 20
B) 19
C) 18
D) 17
E) 16

Rationale: "lets q ' s first number be 14 as per question , q contains 9 multiples of 14 , so let q ' s last number be 126 . ( 14 ∗ 9 ) we have , a n = a + ( n − 1 ) d then 126 = 14 + ( n - 1 ) 7 solving for n , we get n = 17 answer : d"
Answer: D