Q and R are two-digit positive integers that have the same digits but in reverse order. If the positive difference between Q and R is less than 70, what is the greatest possible value of Q minus R?  Choose one
A) 63	B) 64	C) 65	D) 66	E) 67

Rationale: "a two - digit integer ` ` ab ' ' can be expressed algebraically as 10 a + b . q - r = ( 10 a + b ) - ( 10 b + a ) = 9 ( a - b ) < 70 . the greatest multiple of 9 which is less than 70 is 63 . the answer is a ."
Answer: A