Write down the solution for this math problem: Solve -31521 = 10156*k - 10709*k for k.
answer: 57

Write down the solution for this math problem: Solve 215*u = 218*u + 30 for u.
answer: -10

Write down the solution for this math problem: Solve -59*x + 13 = -164 for x.
answer: 3

Write down the solution for this math problem: Solve 0 = -30*c + 3 + 117 for c.
answer:
4