| 17 | x | − | 30 | ( | x | + | 31 | ) | = | 11 | x | − | 1170 |
| 方程左边 = | 17 | x | − | 30 | x | − | 30 | × | 31 |
| = | 17 | x | − | 30 | x | − | 930 |
| = | - | 13 | x | − | 930 |
| - | 13 | x | − | 930 | = | 11 | x | − | 1170 |
| - | 13 | x | − | 11 | x | = | - | 1170 | + | 930 |
| - | 24 | x | = | - | 1170 | + | 930 |
| - | 24 | x | = | - | 240 |
| 240 | = | 24 | x |
| 24 | x | = | 240 |
| x | = | 240 | ÷ | 24 |
| = | 240 | × | 1 24 |
| = | 10 | × | 1 |
| x | = | 10 |