| 15 | ( | 3 | x | − | 8 | ) | − | 4 | ( | 2 | x | + | 3 | ) | = | 6 | ( | 4 | x | − | 4 | ) | − | 4 |
| 方程左边 = | 15 | × | 3 | x | − | 15 | × | 8 | − | 4 | ( | 2 | x | + | 3 | ) |
| = | 45 | x | − | 120 | − | 4 | ( | 2 | x | + | 3 | ) |
| = | 45 | x | − | 120 | − | 4 | × | 2 | x | − | 4 | × | 3 |
| = | 45 | x | − | 120 | − | 8 | x | − | 12 |
| = | 37 | x | − | 132 |
| 37 | x | − | 132 | = | 6 | ( | 4 | x | − | 4 | ) | − | 4 |
| 方程右边 = | 6 | × | 4 | x | − | 6 | × | 4 | − | 4 |
| = | 24 | x | − | 24 | − | 4 |
| = | 24 | x | − | 28 |
| 37 | x | − | 132 | = | 24 | x | − | 28 |
| 37 | x | − | 24 | x | = | - | 28 | + | 132 |
| 13 | x | = | - | 28 | + | 132 |
| 13 | x | = | 104 |
| x | = | 104 | ÷ | 13 |
| = | 104 | × | 1 13 |
| = | 8 | × | 1 |
| x | = | 8 |