Solve 139865*n - 140065*n - 10200 = 0 for n.
Solve this plz.

A: -51

Solve -20615 = 371*b - 9396 + 13638 for b.
Solve this plz.

A: -67

Solve -39*u - 752735 + 753905 = 0 for u.
Solve this plz.

A:
30