Question: What is the solution?

Solve 12 = 3*r + 21 for r.

Answer: -3

Question: What is the solution?

Solve -80*w - 9*w = 98 - 276 for w.

Answer: 2

Question: What is the solution?

Solve -n + 6*n = -0*n for n.

Answer: 0

Question: What is the solution?

Solve -191*m - 36 = -209*m for m.

Answer:
2