| ( | 180 | − | x | ) | + | ( | 180 | − | 2 | x | ) | = | 360 | × | 5 | ÷ | 6 |
| Left side of the equation = | 180 | − | x | + | ( | 180 | − | 2 | x | ) |
| = | 180 | − | x | + | 180 | − | 2 | x |
| = | 360 | − | 3 | x |
| 360 | − | 3 | x | = | 360 | × | 5 | ÷ | 6 |
| Right side of the equation = | 300 |
| 360 | − | 3 | x | = | 300 |
| - | 3 | x | = | 300 | − | 360 |
| - | 3 | x | = | - | 60 |
| 60 | = | 3 | x |
| 3 | x | = | 60 |
| x | = | 60 | ÷ | 3 |
| = | 60 | × | 1 3 |
| = | 20 | × | 1 |
| x | = | 20 |