Q: Solve:
Solve -f + 3*f + 6 = 0 for f.

A: -3

Q: Solve:
Solve -102*n = 41*n + 48*n - 64164 + 56142 for n.

A: 42

Q: Solve:
Solve -139*s + 132*s = 154 for s.

A:
-22