GWD25-37 还是不明白

nicboy

    

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

还是不懂，哪为高手解释一下