| x | − | ( | x | × | 4 5 | ) | − | ( | x | × | 17 20 | ) | − | 10 | = | 405 |
| 方程左边 = | x | − | x | × | 4 5 | − | ( | x | × | 17 20 | ) | − | 10 |
| = | 1 5 | x | − | ( | x | × | 17 20 | ) | − | 10 |
| = | 1 5 | x | − | x | × | 17 20 | − | 10 |
| = | - | 13 20 | x | − | 10 |
| - | 13 20 | x | − | 10 | = | 405 |
| - | 13 20 | x | = | 405 | + | 10 |
| - | 13 20 | x | = | 415 |
| - | 415 | = | 13 20 | x |
13 20 | x | = | - | 415 |
| x | = | - | 415 | ÷ | 13 20 |
| = | - | 415 | × | 20 13 |
| x | = | - | 8300 13 |
| x | = | - 638.461538 |