When the positive integer A is divided by 9 and 8, the remainder is 3 and 4, respectively. When the positive integer B is divided by 9 and 8, the remainder is 3 and 4, respectively. Which of the following must be a factor of A-B?	Select.
A) 48  B) 49  C) 56  D) 65  E) 72
A = 9k+3 = 8j+4   B = 9m+3 = 8n+4   A-B = 9(k-m) = 8(j-n)   Thus A-B is a multiple of 9 and 8, so it is multiple of 72.   The answer is 72.
<result>E</result>
When the positive integer A is divided by 9 and 8, the remainder is 3 and 4, respectively. When the positive integer B is divided by 9 and 8, the remainder is 3 and 4, respectively. Which of the following must be a factor of A-B?