266 25 | X | + | ( | 100 | − | X | ) | × | 168 5 | = | 1380 |
| 方程左边 = | 266 25 | X | + | 100 | × | 168 5 | − | X | × | 168 5 |
| = | 266 25 | X | + | 3360 | − | X | × | 168 5 |
| = | - | 574 25 | X | + | 3360 |
| - | 574 25 | X | + | 3360 | = | 1380 |
| - | 574 25 | X | = | 1380 | − | 3360 |
| - | 574 25 | X | = | - | 1980 |
| 1980 | = | 574 25 | X |
574 25 | X | = | 1980 |
| X | = | 1980 | ÷ | 574 25 |
| = | 1980 | × | 25 574 |
| = | 990 | × | 25 287 |
| X | = | 24750 287 |
| X | = | 86.236934 |