| 8 | ( | 3 | x | − | 12 | ) | + | 4 | ( | - | 16 | x | − | 7 | ) | − | 5 | = | - | 9 |
| 方程左边 = | 8 | × | 3 | x | − | 8 | × | 12 | + | 4 | ( | - | 16 | x | − | 7 | ) | − | 5 |
| = | 24 | x | − | 96 | + | 4 | ( | - | 16 | x | − | 7 | ) | − | 5 |
| = | 24 | x | − | 101 | + | 4 | ( | - | 16 | x | − | 7 | ) |
| = | 24 | x | − | 101 | − | 4 | × | 16 | x | − | 4 | × | 7 |
| = | 24 | x | − | 101 | − | 64 | x | − | 28 |
| = | - | 40 | x | − | 129 |
| - | 40 | x | − | 129 | = | - | 9 |
| - | 40 | x | = | - | 9 | + | 129 |
| - | 40 | x | = | 120 |
| - | 120 | = | 40 | x |
| 40 | x | = | - | 120 |
| x | = | - | 120 | ÷ | 40 |
| = | - | 120 | × | 1 40 |
| = | - | 3 | × | 1 |
| x | = | - | 3 |