| ( | - | 10 | − | 3 | x | ) | − | ( | 10 | − | 2 | x | ) | = | ( | 10 | − | x | ) | − | ( | 10 | − | 2 | x | ) |
| 方程左边 = | - | 10 | − | 3 | x | − | ( | 10 | − | 2 | x | ) |
| = | - | 10 | − | 3 | x | − | 10 | + | 2 | x |
| = | - | 20 | − | 1 | x |
| - | 20 | − | 1 | x | = | ( | 10 | − | x | ) | − | ( | 10 | − | 2 | x | ) |
| 方程右边 = | 10 | − | x | − | ( | 10 | − | 2 | x | ) |
| = | 10 | − | x | − | 10 | + | 2 | x |
| = | 0 | + | 1 | x |
| - | 20 | − | 1 | x | = | 0 | + | 1 | x |
| - | 1 | x | − | 1 | x | = | 20 |
| - | 2 | x | = | 20 |
| - | 20 | = | 2 | x |
| 2 | x | = | - | 20 |
| x | = | - | 20 | ÷ | 2 |
| = | - | 20 | × | 1 2 |
| = | - | 10 | × | 1 |
| x | = | - | 10 |