| 8 | ( | 4 | x | − | 10 | ) | + | 3 | ( | - | 9 | x | + | 1 | ) | + | 7 | = | 15 |
| 方程左边 = | 8 | × | 4 | x | − | 8 | × | 10 | + | 3 | ( | - | 9 | x | + | 1 | ) | + | 7 |
| = | 32 | x | − | 80 | + | 3 | ( | - | 9 | x | + | 1 | ) | + | 7 |
| = | 32 | x | − | 73 | + | 3 | ( | - | 9 | x | + | 1 | ) |
| = | 32 | x | − | 73 | − | 3 | × | 9 | x | + | 3 | × | 1 |
| = | 32 | x | − | 73 | − | 27 | x | + | 3 |
| = | 5 | x | − | 70 |
| 5 | x | − | 70 | = | 15 |
| 5 | x | = | 15 | + | 70 |
| 5 | x | = | 85 |
| x | = | 85 | ÷ | 5 |
| = | 85 | × | 1 5 |
| = | 17 | × | 1 |
| x | = | 17 |