Question:
Solve 0 = 5*z - 0 + 20 for z..

Answer:
-4

Question:
Solve 30*r - 117 = 3 for r..

Answer:
4

Question:
Solve 37*d - 32*d - 901 = -48*d for d..

Answer:
17

Question:
Solve 504*d - 133768 = -166528 for d..

Answer:
-65