| 7 | ( | 3 | − | 10 | ( | 2 | − | 6 | x | ) | ) | + | 2 | ( | 7 | x | − | 7 | ) | = | 301 |
| 方程左边 = | 7 | × | 3 | − | 7 | × | 10 | ( | 2 | − | 6 | x | ) | + | 2 | ( | 7 | x | − | 7 | ) |
| = | 21 | − | 70 | ( | 2 | − | 6 | x | ) | + | 2 | ( | 7 | x | − | 7 | ) |
| = | 21 | − | 70 | × | 2 | + | 70 | × | 6 | x | + | 2 | ( | 7 | x | − | 7 | ) |
| = | 21 | − | 140 | + | 420 | x | + | 2 | ( | 7 | x | − | 7 | ) |
| = | - | 119 | + | 420 | x | + | 2 | ( | 7 | x | − | 7 | ) |
| = | - | 119 | + | 420 | x | + | 2 | × | 7 | x | − | 2 | × | 7 |
| = | - | 119 | + | 420 | x | + | 14 | x | − | 14 |
| = | - | 133 | + | 434 | x |
| - | 133 | + | 434 | x | = | 301 |
| 434 | x | = | 301 | + | 133 |
| 434 | x | = | 434 |
| x | = | 434 | ÷ | 434 |
| = | 434 | × | 1 434 |
| = | 1 | × | 1 |
| x | = | 1 |