| 2 | − | ( | 330821 5000 | − | X | ) | ÷ | 2 | = | 17 5 |
| 方程左边 = | 2 | − | 330821 5000 | × | 1 2 | + | X | × | 1 2 |
| = | 2 | − | 330821 10000 | + | X | × | 1 2 |
| = | - | 310821 10000 | + | 1 2 | X |
| - | 310821 10000 | + | 1 2 | X | = | 17 5 |
1 2 | X | = | 17 5 | + | 310821 10000 |
1 2 | X | = | 344821 10000 |
| X | = | 344821 10000 | ÷ | 1 2 |
| = | 344821 10000 | × | 2 |
| = | 344821 5000 | × | 1 |
| X | = | 344821 5000 |
| X | = | 68.9642 |