| 2 | ( | x | + | x | + | 56 | ) | + | 2 | ( | 90 | − | x | ) | = | 360 |
| 方程左边 = | 2 | x | + | 2 | x | + | 2 | × | 56 | + | 2 | ( | 90 | − | x | ) |
| = | 2 | x | + | 2 | x | + | 112 | + | 2 | ( | 90 | − | x | ) |
| = | 4 | x | + | 112 | + | 2 | ( | 90 | − | x | ) |
| = | 4 | x | + | 112 | + | 2 | × | 90 | − | 2 | x |
| = | 4 | x | + | 112 | + | 180 | − | 2 | x |
| = | 2 | x | + | 292 |
| 2 | x | + | 292 | = | 360 |
| 2 | x | = | 360 | − | 292 |
| 2 | x | = | 68 |
| x | = | 68 | ÷ | 2 |
| = | 68 | × | 1 2 |
| = | 34 | × | 1 |
| x | = | 34 |