Q: Solve:
Solve -63 = 63*u - 72*u for u.

A: 7

Q: Solve:
Solve 643606 + 98894 = -7470*u - 407*u + 1127*u for u.

A: -110

Q: Solve:
Solve -362 + 404 = -14*l for l.

A:
-3