Solve -284*k = -282*k + 24 for k.
Solve this plz.

A: -12

Solve -17*r + 15*r + 39*r = -46*r - 7221 for r.
Solve this plz.

A: -87

Solve -85*f + 1546 + 944 = -2*f for f.
Solve this plz.

A:
30