Q: What is the solution?
Solve -10*c = 13 - 3 for c.

A: -1

Q: What is the solution?
Solve 8*f - 24 - 8 = 0 for f.

A: 4

Q: What is the solution?
Solve -1485*r = 1421*r + 616*r + 253584 for r.

A:
-72