| x | − | 4 | ÷ | 15 | × | x | − | ( | 4 | ÷ | 15 | × | x | − | 20 | ) | = | 510 |
| 方程左边 = | x | − | 4 15 | x | − | ( | 4 | ÷ | 15 | × | x | − | 20 | ) |
| = | 11 15 | x | − | ( | 4 | ÷ | 15 | × | x | − | 20 | ) |
11 15 | x | − | ( | 4 | ÷ | 15 | × | x | − | 20 | ) | = | 510 |
| 方程左边 = | 11 15 | x | − | 4 | ÷ | 15 | × | x | + | 20 |
| = | 11 15 | x | − | 4 15 | x | + | 20 |
| = | 7 15 | x | + | 20 |
7 15 | x | + | 20 | = | 510 |
7 15 | x | = | 510 | − | 20 |
7 15 | x | = | 490 |
| x | = | 490 | ÷ | 7 15 |
| = | 490 | × | 15 7 |
| = | 70 | × | 15 |
| x | = | 1050 |