Solve 79*f - 2692 = -2771 for f.
Solve this plz.

A: -1

Solve 49*y - 81*y + 27*y + 40 = 0 for y.
Solve this plz.

A: 8

Solve -139*r + 146578 = 144771 for r.
Solve this plz.

A:
13