Problem: Math Problem
Solve 644*s - 105*s = -87*s - 18780 for s.

A: -30

Problem: Math Problem
Solve 9 = 20*c - 26 - 32 + 7 for c.

A: 3

Problem: Math Problem
Solve 3398*r + 14145 = 2783*r for r.

A:
-23