| x | + | 1 2 | ( | 180 | − | x | ) | = | 3 | ( | 90 | − | ( | 180 | − | x | ) | ) |
| Left side of the equation = | x | + | 1 2 | × | 180 | − | 1 2 | x |
| = | x | + | 90 | − | 1 2 | x |
| = | 1 2 | x | + | 90 |
1 2 | x | + | 90 | = | 3 | ( | 90 | − | ( | 180 | − | x | ) | ) |
| Right side of the equation = | 3 | × | 90 | − | 3 | ( | 180 | − | x | ) |
| = | 270 | − | 3 | ( | 180 | − | x | ) |
| = | 270 | − | 3 | × | 180 | + | 3 | x |
| = | 270 | − | 540 | + | 3 | x |
| = | - | 270 | + | 3 | x |
1 2 | x | + | 90 | = | - | 270 | + | 3 | x |
1 2 | x | − | 3 | x | = | - | 270 | − | 90 |
| - | 5 2 | x | = | - | 270 | − | 90 |
| - | 5 2 | x | = | - | 360 |
| 360 | = | 5 2 | x |
5 2 | x | = | 360 |
| x | = | 360 | ÷ | 5 2 |
| = | 360 | × | 2 5 |
| = | 72 | × | 2 |
| x | = | 144 |