Q: Solve:
Solve -59*f + 15*f + f - 1591 = 0 for f.

A: -37

Q: Solve:
Solve -18*x = 15 + 21 for x.

A: -2

Q: Solve:
Solve 40*r = 471*r + 225*r - 25584 for r.

A:
39