| 209000000 | = | 69 5 | × | 200 | y | ( | 385 | − | 1 2 | y | ) | + | 330 | × | 763 | × | 343 |
| 方程右边 = | 2760 | y | ( | 385 | − | 1 2 | y | ) | + | 86363970 |
| 209000000 | = | 2760 | y | ( | 385 | − | 1 2 | y | ) | + | 86363970 |
| 方程右边 = | 2760 | y | × | 385 | − | 2760 | y | × | 1 2 | y | + | 86363970 |
| = | 1062600 | y | − | 1380 | y | y | + | 86363970 |
| 209000000 | = | 1062600 | y | − | 1380 | y | y | + | 86363970 |