Write down the solution for this math problem: Solve 15*j - 21*j = 0 for j.
answer: 0

Write down the solution for this math problem: Solve 29 - 107 = 33*n + 21 for n.
answer: -3

Write down the solution for this math problem: Solve -39*h + 39*h - 660 = -60*h for h.
answer: 11

Write down the solution for this math problem: Solve 0 = 49*c - 578 - 465 + 406 for c.
answer:
13