| 1500 | + | 2500 | ( | 50 | − | x | ) | = | 90000 |
| 方程左边 = | 1500 | + | 2500 | × | 50 | − | 2500 | x |
| = | 1500 | + | 125000 | − | 2500 | x |
| = | 126500 | − | 2500 | x |
| 126500 | − | 2500 | x | = | 90000 |
| - | 2500 | x | = | 90000 | − | 126500 |
| - | 2500 | x | = | - | 36500 |
| 36500 | = | 2500 | x |
| 2500 | x | = | 36500 |
| x | = | 36500 | ÷ | 2500 |
| = | 36500 | × | 1 2500 |
| = | 73 | × | 1 5 |
| x | = | 73 5 |
| x | = | 14.6 |