Solve -353*u + 1951 - 1061 = 1243 for u.
Solve this plz.

A: -1

Solve 1137*s + 6668 = 2352*s + 2105*s - 6612 for s.
Solve this plz.

A: 4

Solve -21*z + 616 - 280 = 0 for z.
Solve this plz.

A:
16