Write down the solution for this math problem: Solve -669*u = -648*u - 42 for u.
answer: 2

Write down the solution for this math problem: Solve n + 4 = 4 for n.
answer: 0

Write down the solution for this math problem: Solve -107*y = 59*y + 3818 for y.
answer: -23

Write down the solution for this math problem: Solve 165*k - 1431 = 58*k - 52*k for k.
answer:
9