11 10 | ( | 75 | x | + | 50 | ( | x | − | 15 | ) | ) | = | 9000 |
| 方程左边 = | 11 10 | × | 75 | x | + | 11 10 | × | 50 | ( | x | − | 15 | ) |
| = | 165 2 | x | + | 55 | ( | x | − | 15 | ) |
| = | 165 2 | x | + | 55 | x | − | 55 | × | 15 |
| = | 165 2 | x | + | 55 | x | − | 825 |
| = | 275 2 | x | − | 825 |
275 2 | x | − | 825 | = | 9000 |
275 2 | x | = | 9000 | + | 825 |
275 2 | x | = | 9825 |
| x | = | 9825 | ÷ | 275 2 |
| = | 9825 | × | 2 275 |
| = | 393 | × | 2 11 |
| x | = | 786 11 |
| x | = | 71.454545 |