Write down the solution for this math problem: Solve -78*a - 98 + 20 = 0 for a.
answer: -1

Write down the solution for this math problem: Solve 40*r + 990 - 667 = -539 - 1218 for r.
answer: -52

Write down the solution for this math problem: Solve -74*s - 189 + 28 + 87 = 0 for s.
answer: -1

Write down the solution for this math problem: Solve 281*k - 4480 + 3158 = 9075 for k.
answer:
37