Solve 3*r - 4*r - 35*r + 309 - 1281 = 0 for r.
Solve this plz.

A: -27

Solve 130*k - 7616 = -317*k - 29*k for k.
Solve this plz.

A: 16

Solve 0 = 3381*x + 6489 - 50442 for x.
Solve this plz.

A:
13