| 2 | ( | x | + | 2 | ) | − | 5 | ( | x | + | 2 | ) | = | 20 | − | 8 | ( | x | + | 2 | ) |
| 方程左边 = | 2 | x | + | 2 | × | 2 | − | 5 | ( | x | + | 2 | ) |
| = | 2 | x | + | 4 | − | 5 | ( | x | + | 2 | ) |
| = | 2 | x | + | 4 | − | 5 | x | − | 5 | × | 2 |
| = | 2 | x | + | 4 | − | 5 | x | − | 10 |
| = | - | 3 | x | − | 6 |
| - | 3 | x | − | 6 | = | 20 | − | 8 | ( | x | + | 2 | ) |
| 方程右边 = | 20 | − | 8 | x | − | 8 | × | 2 |
| = | 20 | − | 8 | x | − | 16 |
| = | 4 | − | 8 | x |
| - | 3 | x | − | 6 | = | 4 | − | 8 | x |
| - | 3 | x | + | 8 | x | = | 4 | + | 6 |
| 5 | x | = | 4 | + | 6 |
| 5 | x | = | 10 |
| x | = | 10 | ÷ | 5 |
| = | 10 | × | 1 5 |
| = | 2 | × | 1 |
| x | = | 2 |