posted by ALICIA .
What is the value of C?
Choices: 1, 3, 7, 9, or N/A
Easier if you write it as
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)
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.