| ( | X | + | 3 | ) | ÷ | 28 | = | ( | X | − | 9 | ) | ÷ | 24 |
| 方程左边 = | X | × | 1 28 | + | 3 | × | 1 28 |
| = | X | × | 1 28 | + | 3 28 |
1 28 | X | + | 3 28 | = | ( | X | − | 9 | ) | ÷ | 24 |
| 方程右边 = | X | × | 1 24 | − | 9 | × | 1 24 |
| = | X | × | 1 24 | − | 3 8 |
1 28 | X | + | 3 28 | = | 1 24 | X | − | 3 8 |
1 28 | X | − | 1 24 | X | = | - | 3 8 | − | 3 28 |
| - | 1 168 | X | = | - | 3 8 | − | 3 28 |
| - | 1 168 | X | = | - | 27 56 |
27 56 | = | 1 168 | X |
1 168 | X | = | 27 56 |
| X | = | 27 56 | ÷ | 1 168 |
| = | 27 56 | × | 168 |
| = | 27 | × | 3 |
| X | = | 81 |