| ( | X | − | 1182 125 | ) | ÷ | X | = | 21 5 |
| 方程两边同时乘以: | X |
| ( | X | − | 1182 125 | ) | = | 21 5 | X |
| X | − | 1182 125 | = | 21 5 | X |
| X | − | 21 5 | X | = | 1182 125 |
| - | 16 5 | X | = | 1182 125 |
| - | 1182 125 | = | 16 5 | X |
16 5 | X | = | - | 1182 125 |
| X | = | - | 1182 125 | ÷ | 16 5 |
| = | - | 1182 125 | × | 5 16 |
| = | - | 591 25 | × | 1 8 |
| X | = | - | 591 200 |
| X | = | - 2.955 |