Question:
Solve 2*r = -39 + 41 for r..

Answer:
1

Question:
Solve -192*k + 900*k = -32506 + 12682 for k..

Answer:
-28

Question:
Solve 13*z - 21*z - 52 = 5*z for z..

Answer:
-4

Question:
Solve 57 = 52*x - 33*x for x..

Answer:
3