QUESTION: Math problem: Solve -39 = -c + 40*c for c.
ANS: -1
QUESTION: Math problem: Solve 9 = 7*o + 16 for o.
ANS: -1
QUESTION: Math problem: Solve 12756 - 7508 = 100*l + 288*l - 25404 for l.
ANS: 79
QUESTION: Math problem: Solve 43*d + 3 = 40*d for d.
ANS:
-1