Write down the solution for this math problem: Solve 289*a + 51*a - 9330 = 29*a for a.
answer: 30

Write down the solution for this math problem: Solve 357*s = 361*s + 20 for s.
answer: -5

Write down the solution for this math problem: Solve -291*s + 20 = -281*s for s.
answer: 2

Write down the solution for this math problem: Solve -159*d + 31*d = -1536 for d.
answer:
12