Write down the solution for this math problem: Solve 4 = 308*c - 306*c for c.
answer: 2

Write down the solution for this math problem: Solve 0 = 12*n - 11*n + 2 for n.
answer: -2

Write down the solution for this math problem: Solve -20*r + 2328 = -147*r + 550 for r.
answer: -14

Write down the solution for this math problem: Solve -597*r + 333 = -634*r for r.
answer:
-9