Question: What is the solution?

Solve 648*u + 563*u = 1871*u - 567*u + 3999 for u.

Answer: -43

Question: What is the solution?

Solve 12 = -6*c + 10*c for c.

Answer: 3

Question: What is the solution?

Solve -102*p - 2300 = -202*p for p.

Answer: 23

Question: What is the solution?

Solve 0 = -135*f + 24625 - 27055 for f.

Answer:
-18