| ( | 22 | − | x | ) | + | ( | 23 | − | x | ) | + | ( | 16 | − | x | ) | + | ( | 20 | − | x | ) | = | 72 | − | x |
| 方程左边 = | 22 | − | x | + | ( | 23 | − | x | ) | + | ( | 16 | − | x | ) | + | ( | 20 | − | x | ) |
| = | 22 | − | x | + | 23 | − | x | + | ( | 16 | − | x | ) | + | ( | 20 | − | x | ) |
| = | 45 | − | 2 | x | + | ( | 16 | − | x | ) | + | ( | 20 | − | x | ) |
| = | 45 | − | 2 | x | + | 16 | − | x | + | ( | 20 | − | x | ) |
| = | 61 | − | 3 | x | + | ( | 20 | − | x | ) |
| = | 61 | − | 3 | x | + | 20 | − | x |
| = | 81 | − | 4 | x |
| 81 | − | 4 | x | = | 72 | − | x |
| - | 4 | x | + | x | = | 72 | − | 81 |
| - | 3 | x | = | 72 | − | 81 |
| - | 3 | x | = | - | 9 |
| 9 | = | 3 | x |
| 3 | x | = | 9 |
| x | = | 9 | ÷ | 3 |
| = | 9 | × | 1 3 |
| = | 3 | × | 1 |
| x | = | 3 |