| 2 | − | 7 | ( | 7 | + | 65 | ÷ | ( | - | 2 | x | + | 1 | ) | ) | = | - | 12 |
| 2 | − | 7 | × | 7 | − | 7 | × | 65 | ÷ | ( | - | 2 | x | + | 1 | ) | = | - | 12 |
| 2 | − | 49 | − | 455 | ÷ | ( | - | 2 | x | + | 1 | ) | = | - | 12 |
| - | 47 | − | 455 | ÷ | ( | - | 2 | x | + | 1 | ) | = | - | 12 |
| 方程两边同时乘以: | ( | - | 2 | x | + | 1 | ) |
| - | 47 | ( | - | 2 | x | + | 1 | ) | − | 455 | = | - | 12 | ( | - | 2 | x | + | 1 | ) |
| 47 | × | 2 | x | − | 47 | × | 1 | − | 455 | = | - | 12 | ( | - | 2 | x | + | 1 | ) |
| 47 | × | 2 | x | − | 47 | × | 1 | − | 455 | = | 12 | × | 2 | x | − | 12 | × | 1 |
| 94 | x | − | 47 | − | 455 | = | 24 | x | − | 12 |
| 94 | x | − | 502 | = | 24 | x | − | 12 |
| 94 | x | − | 24 | x | = | - | 12 | + | 502 |
| 70 | x | = | - | 12 | + | 502 |
| 70 | x | = | 490 |
| x | = | 490 | ÷ | 70 |
| = | 490 | × | 1 70 |
| = | 7 | × | 1 |
| x | = | 7 |