| - | 2 | ( | x | − | 4 | ) | = | 3 | − | ( | 7 | − | 2 | x | ) |
| 方程左边 = | - | 2 | x | + | 2 | × | 4 |
| = | - | 2 | x | + | 8 |
| - | 2 | x | + | 8 | = | 3 | − | ( | 7 | − | 2 | x | ) |
| 方程右边 = | 3 | − | 7 | + | 2 | x |
| = | - | 4 | + | 2 | x |
| - | 2 | x | + | 8 | = | - | 4 | + | 2 | x |
| - | 2 | x | − | 2 | x | = | - | 4 | − | 8 |
| - | 4 | x | = | - | 4 | − | 8 |
| - | 4 | x | = | - | 12 |
| 12 | = | 4 | x |
| 4 | x | = | 12 |
| x | = | 12 | ÷ | 4 |
| = | 12 | × | 1 4 |
| = | 3 | × | 1 |
| x | = | 3 |