Write down the solution for this math problem: Solve u + 134 = 129 for u.
answer: -5

Write down the solution for this math problem: Solve 1347*f - 210 = 1368*f for f.
answer: -10

Write down the solution for this math problem: Solve -28 = -155432*x + 155446*x for x.
answer: -2

Write down the solution for this math problem: Solve 246561 - 247851 = -43*r for r.
answer:
30