Question:
Solve 0 = -12*c + 4*c + 40 for c..

Answer:
5

Question:
Solve 13*h - 32*h = -22*h for h..

Answer:
0

Question:
Solve -8*o = 2*o + 40 for o..

Answer:
-4

Question:
Solve -456 = 4*i - 460 for i..

Answer:
1