GWD25-37 还是不明白

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

Answer  E

问C是多少？

AB和BA都是两位数，但是和是一个三位数，两位数加两位数后的和的第百位只能是1，所以A=1。即1B+B1=11C。由此推出B只能为9，最终推出C为0.即：19+91=110.所以选E