18 100 | x | + | ( | 500 | − | x | ) | × | 23 100 | = | 500 | × | 20 100 |
| 方程左边 = | 18 100 | x | + | 500 | × | 23 100 | − | x | × | 23 100 |
| = | 18 100 | x | + | 115 | − | x | × | 23 100 |
| = | - | 1 20 | x | + | 115 |
| - | 1 20 | x | + | 115 | = | 500 | × | 20 100 |
| 方程右边 = | 100 |
| - | 1 20 | x | + | 115 | = | 100 |
| - | 1 20 | x | = | 100 | − | 115 |
| - | 1 20 | x | = | - | 15 |
| 15 | = | 1 20 | x |
1 20 | x | = | 15 |
| x | = | 15 | ÷ | 1 20 |
| = | 15 | × | 20 |
| x | = | 300 |