Question:
Solve 0 = 146*u - 447*u - 3913 for u..

Answer:
-13

Question:
Solve 404*k + 13913 - 9128 = -337*k - 21891 for k..

Answer:
-36

Question:
Solve -349985*s - 16731 = -350154*s for s..

Answer:
99

Question:
Solve -2*z + 397 = 407 for z..

Answer:
-5