| ( | - | 6 | ) | ( | x | + | 5 | ) | + | 7 | ( | x | − | 5 | ) | = | 7 | ( | x | − | 18 | ) | + | 61 |
| 方程左边 = | - | 6 | ( | x | + | 5 | ) | + | 7 | ( | x | − | 5 | ) |
| = | - | 6 | x | − | 6 | × | 5 | + | 7 | ( | x | − | 5 | ) |
| = | - | 6 | x | − | 30 | + | 7 | ( | x | − | 5 | ) |
| = | - | 6 | x | − | 30 | + | 7 | x | − | 7 | × | 5 |
| = | - | 6 | x | − | 30 | + | 7 | x | − | 35 |
| = | 1 | x | − | 65 |
| 1 | x | − | 65 | = | 7 | ( | x | − | 18 | ) | + | 61 |
| 方程右边 = | 7 | x | − | 7 | × | 18 | + | 61 |
| = | 7 | x | − | 126 | + | 61 |
| = | 7 | x | − | 65 |
| 1 | x | − | 65 | = | 7 | x | − | 65 |
| 1 | x | − | 7 | x | = | - | 65 | + | 65 |
| - | 6 | x | = | - | 65 | + | 65 |
| - | 6 | x | = | - | 0 |
| 0 | = | 6 | x |
| 6 | x | = | 0 |
| x | = | 0 | ÷ | 6 |
| = | 0 | × | 1 6 |
| x | = | 0 |