| 8 | ( | 6 | + | 7 | ( | 12 | − | x | ) | ) | + | 1 | = | - | 7 |
| 方程左边 = | 8 | × | 6 | + | 8 | × | 7 | ( | 12 | − | x | ) | + | 1 |
| = | 48 | + | 56 | ( | 12 | − | x | ) | + | 1 |
| = | 49 | + | 56 | ( | 12 | − | x | ) |
| = | 49 | + | 56 | × | 12 | − | 56 | x |
| = | 49 | + | 672 | − | 56 | x |
| = | 721 | − | 56 | x |
| 721 | − | 56 | x | = | - | 7 |
| - | 56 | x | = | - | 7 | − | 721 |
| - | 56 | x | = | - | 728 |
| 728 | = | 56 | x |
| 56 | x | = | 728 |
| x | = | 728 | ÷ | 56 |
| = | 728 | × | 1 56 |
| = | 13 | × | 1 |
| x | = | 13 |