Question:
Solve 38*d = 77*d - 429 for d..

Answer:
11

Question:
Solve -13*f - 50 = 37*f for f..

Answer:
-1

Question:
Solve -497 + 797 = 25*r for r..

Answer:
12

Question:
Solve -6*b = 3124 - 3112 for b..

Answer:
-2