Write down the solution for this math problem: Solve 387*n + 536 = 521*n for n.
answer: 4

Write down the solution for this math problem: Solve 0 = -179*f + 299*f + 1560 for f.
answer: -13

Write down the solution for this math problem: Solve -1223*r - 228 = -1242*r for r.
answer: 12

Write down the solution for this math problem: Solve -1293 + 378 = -61*n for n.
answer:
15