| ( | 4 | X | − | 5 | ) | ÷ | ( | 5 | X | − | 10 | ) | = | 9 | ÷ | 10 |
| 方程两边同时乘以: | ( | 5 | X | − | 10 | ) |
| ( | 4 | X | − | 5 | ) | = | 9 | ÷ | 10 | × | ( | 5 | X | − | 10 | ) |
| 4 | X | − | 5 | = | 9 | ÷ | 10 | × | ( | 5 | X | − | 10 | ) |
| 4 | X | − | 5 | = | 9 | ÷ | 10 | × | 5 | X | − | 9 | ÷ | 10 | × | 10 |
| 4 | X | − | 5 | = | 9 2 | X | − | 9 |
| 4 | X | − | 9 2 | X | = | - | 9 | + | 5 |
| - | 1 2 | X | = | - | 9 | + | 5 |
| - | 1 2 | X | = | - | 4 |
| 4 | = | 1 2 | X |
1 2 | X | = | 4 |
| X | = | 4 | ÷ | 1 2 |
| = | 4 | × | 2 |
| X | = | 8 |