| X | ( | 1 | − | 20 100 | ) | × | 20 100 | = | X | − | 20000 |
| 方程左边 = | X | × | 1 | × | 20 100 | − | X | × | 20 100 | × | 20 100 |
| = | X | × | 1 5 | − | X | × | 1 25 |
| = | 4 25 | X |
4 25 | X | = | X | − | 20000 |
4 25 | X | − | X | = | - | 20000 |
| - | 21 25 | X | = | - | 20000 |
| 20000 | = | 21 25 | X |
21 25 | X | = | 20000 |
| X | = | 20000 | ÷ | 21 25 |
| = | 20000 | × | 25 21 |
| X | = | 500000 21 |
| X | = | 23809.52381 |