Solve 59 = 16*s - 21 for s.
Solve this plz.

A: 5

Solve -31*n - 45 - 172 = 0 for n.
Solve this plz.

A: -7

Solve 1223*a + 1227*a - 2442*a + 104 = 0 for a.
Solve this plz.

A:
-13