Question:
Solve 478*r + 298*r + 427 = 4307 for r..

Answer:
5

Question:
Solve 146*h = -151*h + 257*h + 520 for h..

Answer:
13

Question:
Solve -h = 2*h + 12 for h..

Answer:
-4

Question:
Solve 0*r - 5 = r for r..

Answer:
-5