Solve -504*u = -498*u - 18 for u.
Solve this plz.

A: 3

Solve -9*r - 131*r + 157*r + 646 = 0 for r.
Solve this plz.

A: -38

Solve -173*r = 50*r - 0*r + 27652 for r.
Solve this plz.

A:
-124