| 10 | x | + | 10 | x | × | 10 100 | + | 90 100 | × | 10 | ( | 200 | − | x | ) | = | 0 |
| 方程左边 = | 10 | x | + | 1 | x | + | 9 | ( | 200 | − | x | ) |
| = | 11 | x | + | 9 | ( | 200 | − | x | ) |
| 11 | x | + | 9 | ( | 200 | − | x | ) | = | 0 |
| 方程左边 = | 11 | x | + | 9 | × | 200 | − | 9 | x |
| = | 11 | x | + | 1800 | − | 9 | x |
| = | 2 | x | + | 1800 |
| 2 | x | + | 1800 | = | 0 |
| 2 | x | = | 0 | − | 1800 |
| 2 | x | = | - | 1800 |
| x | = | - | 1800 | ÷ | 2 |
| = | - | 1800 | × | 1 2 |
| = | - | 900 | × | 1 |
| x | = | - | 900 |