Question:
Solve 0*d = 5*d - 20 for d..

Answer:
4

Question:
Solve 0 = -61*i + 15*i + 871 - 89 for i..

Answer:
17

Question:
Solve -4*t = -24*t - 174 + 34 for t..

Answer:
-7

Question:
Solve -4 = -s - 1 for s..

Answer:
3