| 100 | + | ( | x | − | 100 | ) | × | 10 100 | = | 200 | + | ( | x | − | 100 | − | 200 | ) | × | 10 100 |
| 方程左边 = | 100 | + | x | × | 10 100 | − | 100 | × | 10 100 |
| = | 100 | + | x | × | 10 100 | − | 10 |
| = | 90 | + | 10 100 | x |
| 90 | + | 10 100 | x | = | 200 | + | ( | x | − | 100 | − | 200 | ) | × | 10 100 |
| 方程右边 = | 200 | + | x | × | 10 100 | − | 100 | × | 10 100 | − | 200 | × | 10 100 |
| = | 200 | + | x | × | 10 100 | − | 10 | − | 20 |
| = | 170 | + | 10 100 | x |
| 90 | + | 10 100 | x | = | 170 | + | 10 100 | x |
10 100 | x | − | 10 100 | x | = | 170 | − | 90 |
| 0 | x | = | 170 | − | 90 |
| 0 | x | = | 80 |