| x | − | 20 | × | 69 20 | + | 20 | × | 207 100 | − | 19 10 | x | = | 409 20 |
| 方程左边 = | x | − | 69 | + | 207 5 | − | 19 10 | x |
| = | - | 9 10 | x | − | 138 5 |
| - | 9 10 | x | − | 138 5 | = | 409 20 |
| - | 9 10 | x | = | 409 20 | + | 138 5 |
| - | 9 10 | x | = | 961 20 |
| - | 961 20 | = | 9 10 | x |
9 10 | x | = | - | 961 20 |
| x | = | - | 961 20 | ÷ | 9 10 |
| = | - | 961 20 | × | 10 9 |
| = | - | 961 2 | × | 1 9 |
| x | = | - | 961 18 |
| x | = | - 53.388889 |