Question:
Solve -43*u + 133 = 4 for u..

Answer:
3

Question:
Solve 40*k = 54*k + 28 for k..

Answer:
-2

Question:
Solve 37669*z = 37748*z + 2291 for z..

Answer:
-29

Question:
Solve -42 = -450*r + 443*r for r..

Answer:
6