Q: What is the solution?
Solve 4*i = -4*i + 24 for i.

A: 3

Q: What is the solution?
Solve -27 = -2*r - 27 for r.

A: 0

Q: What is the solution?
Solve 15*u - 67*u = -48*u - 68 for u.

A:
17