| 8 | ( | 3 | x | − | 1 | ) | − | 9 | ( | 5 | x | − | 11 | ) | − | 2 | ( | 2 | x | − | 7 | ) | = | 30 |
| 方程左边 = | 8 | × | 3 | x | − | 8 | × | 1 | − | 9 | ( | 5 | x | − | 11 | ) | − | 2 | ( | 2 | x | − | 7 | ) |
| = | 24 | x | − | 8 | − | 9 | ( | 5 | x | − | 11 | ) | − | 2 | ( | 2 | x | − | 7 | ) |
| = | 24 | x | − | 8 | − | 9 | × | 5 | x | + | 9 | × | 11 | − | 2 | ( | 2 | x | − | 7 | ) |
| = | 24 | x | − | 8 | − | 45 | x | + | 99 | − | 2 | ( | 2 | x | − | 7 | ) |
| = | - | 21 | x | + | 91 | − | 2 | ( | 2 | x | − | 7 | ) |
| = | - | 21 | x | + | 91 | − | 2 | × | 2 | x | + | 2 | × | 7 |
| = | - | 21 | x | + | 91 | − | 4 | x | + | 14 |
| = | - | 25 | x | + | 105 |
| - | 25 | x | + | 105 | = | 30 |
| - | 25 | x | = | 30 | − | 105 |
| - | 25 | x | = | - | 75 |
| 75 | = | 25 | x |
| 25 | x | = | 75 |
| x | = | 75 | ÷ | 25 |
| = | 75 | × | 1 25 |
| = | 3 | × | 1 |
| x | = | 3 |