Q: Solve:
Solve 689*b - 6926 = -18855 - 43191 for b.

A: -80

Q: Solve:
Solve -40 - 20 = 30*r for r.

A: -2

Q: Solve:
Solve -142*x = 239*x - 111*x + 50*x + 11840 for x.

A:
-37