| 6300 | ÷ | 87 4 | × | ( | X | × | 80 100 | + | ( | 87 4 | − | X | ) | ) | = | 5813 |
| 方程左边 = | 8400 29 | ( | X | × | 80 100 | + | ( | 87 4 | − | X | ) | ) |
8400 29 | ( | X | × | 80 100 | + | ( | 87 4 | − | X | ) | ) | = | 5813 |
| 方程左边 = | 8400 29 | X | × | 80 100 | + | 8400 29 | ( | 87 4 | − | X | ) |
| = | 6720 29 | X | + | 8400 29 | ( | 87 4 | − | X | ) |
| = | 6720 29 | X | + | 8400 29 | × | 87 4 | − | 8400 29 | X |
| = | 6720 29 | X | + | 6300 | − | 8400 29 | X |
| = | - | 1680 29 | X | + | 6300 |
| - | 1680 29 | X | + | 6300 | = | 5813 |
| - | 1680 29 | X | = | 5813 | − | 6300 |
| - | 1680 29 | X | = | - | 487 |
| 487 | = | 1680 29 | X |
1680 29 | X | = | 487 |
| X | = | 487 | ÷ | 1680 29 |
| = | 487 | × | 29 1680 |
| X | = | 14123 1680 |
| X | = | 8.406548 |