Question:
Solve -3*s - 5 = -4*s for s..

Answer:
5

Question:
Solve -20*t + 102 = 22 for t..

Answer:
4

Question:
Solve -2 = -10*r + 12*r for r..

Answer:
-1

Question:
Solve -13*z + 244 = 48*z for z..

Answer:
4