Question: What is the solution?

Solve 18*r + 6474 = 129*r + 55*r for r.

Answer: 39

Question: What is the solution?

Solve 0 = 74*s - 61*s + 13 for s.

Answer: -1

Question: What is the solution?

Solve -325*y = -511*y - 5580 for y.

Answer: -30

Question: What is the solution?

Solve 7160*o - 369 = 6791*o for o.

Answer:
1