| 3 | ( | x | − | 7 | ) | − | 2 | ( | 9 | − | 4 | ( | 2 | − | x | ) | ) | = | 22 |
| 方程左边 = | 3 | x | − | 3 | × | 7 | − | 2 | ( | 9 | − | 4 | ( | 2 | − | x | ) | ) |
| = | 3 | x | − | 21 | − | 2 | ( | 9 | − | 4 | ( | 2 | − | x | ) | ) |
| = | 3 | x | − | 21 | − | 2 | × | 9 | + | 2 | × | 4 | ( | 2 | − | x | ) |
| = | 3 | x | − | 21 | − | 18 | + | 8 | ( | 2 | − | x | ) |
| = | 3 | x | − | 39 | + | 8 | ( | 2 | − | x | ) |
| = | 3 | x | − | 39 | + | 8 | × | 2 | − | 8 | x |
| = | 3 | x | − | 39 | + | 16 | − | 8 | x |
| = | - | 5 | x | − | 23 |
| - | 5 | x | − | 23 | = | 22 |
| - | 5 | x | = | 22 | + | 23 |
| - | 5 | x | = | 45 |
| - | 45 | = | 5 | x |
| 5 | x | = | - | 45 |
| x | = | - | 45 | ÷ | 5 |
| = | - | 45 | × | 1 5 |
| = | - | 9 | × | 1 |
| x | = | - | 9 |