| 55 | × | 300 | × | 3 5 | − | ( | X | − | 55 | ) | × | 300 | = | 300 | X | × | 7 20 |
| 方程左边 = | 9900 | − | ( | X | − | 55 | ) | × | 300 |
| 9900 | − | ( | X | − | 55 | ) | × | 300 | = | 300 | X | × | 7 20 |
| 方程左边 = | 9900 | − | X | × | 300 | + | 55 | × | 300 |
| = | 9900 | − | X | × | 300 | + | 16500 |
| = | 26400 | − | 300 | X |
| 26400 | − | 300 | X | = | 300 | X | × | 7 20 |
| 方程右边 = | 105 | X |
| 26400 | − | 300 | X | = | 105 | X |
| - | 300 | X | − | 105 | X | = | - | 26400 |
| - | 405 | X | = | - | 26400 |
| 26400 | = | 405 | X |
| 405 | X | = | 26400 |
| X | = | 26400 | ÷ | 405 |
| = | 26400 | × | 1 405 |
| = | 1760 | × | 1 27 |
| X | = | 1760 27 |
| X | = | 65.185185 |