| 200 | − | ( | 15 100 | − | X | ) | = | 100 | − | ( | X | − | 10 100 | ) |
| 方程左边 = | 200 | − | 15 100 | + | X |
| = | 3997 20 | + | X |
3997 20 | + | X | = | 100 | − | ( | X | − | 10 100 | ) |
| 方程右边 = | 100 | − | X | + | 10 100 |
| = | 1001 10 | − | X |
3997 20 | + | X | = | 1001 10 | − | X |
| X | + | X | = | 1001 10 | − | 3997 20 |
| 2 | X | = | 1001 10 | − | 3997 20 |
| 2 | X | = | - | 399 4 |
| X | = | - | 399 4 | ÷ | 2 |
| = | - | 399 4 | × | 1 2 |
| X | = | - | 399 8 |
| X | = | - 49.875 |