Write down the solution for this math problem: Solve -31*b + 172*b - 558 = -35*b - 8478 for b.
answer: -45

Write down the solution for this math problem: Solve 0 = -42*i - 646 - 229 - 343 for i.
answer: -29

Write down the solution for this math problem: Solve -3*r + 10*r - 83*r = 456 for r.
answer: -6

Write down the solution for this math problem: Solve -205*b + 295*b = -602*b + 6920 for b.
answer:
10