The difference between a two-digit number and the number obtained by interchanging the positions of its digits is 27. What is the difference between the two digits of that number? Select:
A) 3	B) 5	C) 6	D) 8	E) 9

Rationale: "sol . let the ten ’ s digit be x and unit ’ s digit be y , then , ( 10 x + y ) - ( 10 y + x ) = 27 ⇔ 9 ( x - y ) = 27 ⇔ x - y = 3 answer a"
Answer: A