| ( | 200 | − | X | ) | × | 20 100 | = | 200 | × | 16 100 |
| 方程左边 = | 200 | × | 20 100 | − | X | × | 20 100 |
| = | 40 | − | X | × | 20 100 |
| 40 | − | 20 100 | X | = | 200 | × | 16 100 |
| 方程右边 = | 32 |
| 40 | − | 20 100 | X | = | 32 |
| - | 20 100 | X | = | 32 | − | 40 |
| - | 20 100 | X | = | - | 8 |
| 8 | = | 20 100 | X |
20 100 | X | = | 8 |
| X | = | 8 | ÷ | 20 100 |
| = | 8 | × | 100 20 |
| = | 2 | × | 100 5 |
| X | = | 200 5 |
| X | = | 40 |