Q: What is the solution?
Solve -47 = -r + 10*r + 25 for r.

A: -8

Q: What is the solution?
Solve -232*l + 217*l = -240 for l.

A: 16

Q: What is the solution?
Solve 161 - 7 = -21*z - 56*z for z.

A:
-2