Solve 315 = -846*c + 825*c for c.
Solve this plz.

A: -15

Solve -493*z - 9547 - 9680 = 0 for z.
Solve this plz.

A: -39

Solve 11883 = -10001*a + 10238*a - 8025 for a.
Solve this plz.

A:
84