Q: What is the solution?
Solve -13*f = -21*f + 40 for f.

A: 5

Q: What is the solution?
Solve -242 = 40*d + 65*d + 1333 for d.

A: -15

Q: What is the solution?
Solve 945*z - 714 + 2330 + 2581 = -454*z for z.

A:
-3