QUESTION: Math problem: Solve r - 7*r = 0 for r.
ANS: 0
QUESTION: Math problem: Solve -12566*c + 190 = -12471*c for c.
ANS: 2
QUESTION: Math problem: Solve -29*x + 200 = x - 5*x for x.
ANS: 8
QUESTION: Math problem: Solve 0 = -2*r - 1 - 7 for r.
ANS:
-4