Write down the solution for this math problem: Solve 51*v + 670 = 323 - 571 for v.
answer: -18

Write down the solution for this math problem: Solve 66 = 20*u + 20*u - 46*u for u.
answer: -11

Write down the solution for this math problem: Solve 28*r - 34*r = 30 for r.
answer: -5

Write down the solution for this math problem: Solve 461 = -340*k + 321 + 1160 for k.
answer:
3