Digit-based algebra: finding digits satisfying a three-fold repeated addition producing a repdigit sum.
The addition represents 3 x (100A+10B+C) = 111C (since CCC = C x 111, a three-digit repdigit). Expanding: 300A+30B+3C=111C, so 300A+30B=108C, or dividing by 6:...
Full option-by-option analysis available to enrolled students.