| ( | 24000 | − | X | ) | ÷ | X | × | 100 100 | = | 20 100 |
| 方程两边同时乘以: | X |
| ( | 24000 | − | X | ) | × | 100 100 | = | 20 100 | X |
| 24000 | × | 100 100 | − | X | × | 100 100 | = | 20 100 | X |
| 24000 | − | X | × | 100 100 | = | 20 100 | X |
| - | 100 100 | X | − | 20 100 | X | = | - | 24000 |
| - | 6 5 | X | = | - | 24000 |
| 24000 | = | 6 5 | X |
6 5 | X | = | 24000 |
| X | = | 24000 | ÷ | 6 5 |
| = | 24000 | × | 5 6 |
| = | 4000 | × | 5 |
| X | = | 20000 |