Write down the solution for this math problem: Solve 3*f + 391 = 379 for f.
answer: -4

Write down the solution for this math problem: Solve 83 - 308 = 22*q - 115 for q.
answer: -5

Write down the solution for this math problem: Solve 17*b - 8 = 21*b for b.
answer: -2

Write down the solution for this math problem: Solve 639*z + 2363 = 23076 - 5963 + 38926 for z.
answer:
84