Question:
Solve 0 = 697*c - 483*c + 642 for c..

Answer:
-3

Question:
Solve -121183*s + 121197*s = -224 for s..

Answer:
-16

Question:
Solve 380435*d - 380529*d = 1974 for d..

Answer:
-21

Question:
Solve -150 = -13*u - 124 for u..

Answer:
2