Q37. AB

+BA

AAC

In the correctly worked addition problem shown, where the sum of the two-digit positive integers AB and BA is the three-digit integer AAC, and A, B, and C are different digits, what is the units digit of the integer AAC?

A. 9

B. 6

C. 3

D. 2

E. 0

这个题目也不会，答案E,觉得25套的数学比较难

First thought: A = 1 (9 + 9 = 18 so the hundredth digit must be 1)
so we have 1B + B1 = 11C. (1+B) + (1+B) * 10 = 11C
=> x + 10x = 11C
let x = 10 => C = 0
let x = 11 => impossible

E