| 10 | ( | - | 2 | x | − | 3 | ) | + | 7 | ( | - | 2 | x | − | 15 | ) | + | 2 | = | 3 |
| 方程左边 = | - | 10 | × | 2 | x | − | 10 | × | 3 | + | 7 | ( | - | 2 | x | − | 15 | ) | + | 2 |
| = | - | 20 | x | − | 30 | + | 7 | ( | - | 2 | x | − | 15 | ) | + | 2 |
| = | - | 20 | x | − | 28 | + | 7 | ( | - | 2 | x | − | 15 | ) |
| = | - | 20 | x | − | 28 | − | 7 | × | 2 | x | − | 7 | × | 15 |
| = | - | 20 | x | − | 28 | − | 14 | x | − | 105 |
| = | - | 34 | x | − | 133 |
| - | 34 | x | − | 133 | = | 3 |
| - | 34 | x | = | 3 | + | 133 |
| - | 34 | x | = | 136 |
| - | 136 | = | 34 | x |
| 34 | x | = | - | 136 |
| x | = | - | 136 | ÷ | 34 |
| = | - | 136 | × | 1 34 |
| = | - | 4 | × | 1 |
| x | = | - | 4 |