| ( | 24 | − | X | ) | ÷ | 24 | = | ( | 20 | − | X | ) | ÷ | 20 |
| 方程左边 = | 24 | × | 1 24 | − | X | × | 1 24 |
| = | 1 | − | X | × | 1 24 |
| 1 | − | 1 24 | X | = | ( | 20 | − | X | ) | ÷ | 20 |
| 方程右边 = | 20 | × | 1 20 | − | X | × | 1 20 |
| = | 1 | − | X | × | 1 20 |
| 1 | − | 1 24 | X | = | 1 | − | 1 20 | X |
| - | 1 24 | X | + | 1 20 | X | = | 1 | − | 1 |
1 120 | X | = | 1 | − | 1 |
1 120 | X | = | 0 |
| X | = | 0 | ÷ | 1 120 |
| = | 0 | × | 120 |
| X | = | 0 |