| 180 | ( | n | − | 2 | ) | + | 180 | − | 180 | ( | n | − | 2 | ) | ÷ | n | = | 1350 |
| Multiply both sides of the equation by: | n |
| 180 | ( | n | − | 2 | ) | n | + | 180 | n | − | 180 | ( | n | − | 2 | ) | = | 1350 | n |
| 180 | n | n | − | 180 | × | 2 | n | + | 180 | n | − | 180 | ( | n | − | 2 | ) | = | 1350 | n |
| 180 | n | n | − | 360 | n | + | 180 | n | − | 180 | ( | n | − | 2 | ) | = | 1350 | n |
| 180 | n | n | − | 180 | n | − | 180 | ( | n | − | 2 | ) | = | 1350 | n |
| 180 | n | n | − | 180 | n | − | 180 | n | + | 180 | × | 2 | = | 1350 | n |
| 180 | n | n | − | 180 | n | − | 180 | n | + | 360 | = | 1350 | n |
| 180 | n | n | − | 360 | n | + | 360 | = | 1350 | n |