Write down the solution for this math problem: Solve 9*u = 16*u - 13*u for u.
answer: 0

Write down the solution for this math problem: Solve 15 = -c + 16 for c.
answer: 1

Write down the solution for this math problem: Solve -42300 = -7103*i + 6398*i for i.
answer: 60

Write down the solution for this math problem: Solve -10*f - 12 = -6*f for f.
answer:
-3