AB+CD=AAA

Question

What is the value of C?

Choices: 1, 3, 7, 9, or N/A

Answer 1

Easier if you write it as

_AB
_CD+
____
AAA

The largest A+C can be is 18 (1 carried plus say A or C=9 and A or C=8) so A must =1 (it can't=0)

re-write

_1B
_CD+
____
111

In order for 1+C=11, C =9 with 1 carried from B+D.

We don't need to know what B and D are.