This problem has been troubling me for a while. Strategy Guide: Number Properties, page 134, #20 x has a remainder of 5 when divided by 9. y has a remainder of 7 when divided by 9. what is the remainder when x-y is divided by 9 My Approach: X can be 5, 14, 23, 32, 41... etc Y can be 7, 16, 25, 34, 4...