| 4 | x | × | 2 | − | x | × | 2 | = | ( | 10 | + | x | ) | ( | 10 | + | x | ) |
| 方程左边 = | 8 | x | − | x | × | 2 |
| = | 6 | x |
| 6 | x | = | ( | 10 | + | x | ) | ( | 10 | + | x | ) |
| 方程右边 = | 10 | ( | 10 | + | x | ) | + | x | ( | 10 | + | x | ) |
| = | 10 | × | 10 | + | 10 | x | + | x | ( | 10 | + | x | ) |
| = | 100 | + | 10 | x | + | x | ( | 10 | + | x | ) |
| = | 100 | + | 10 | x | + | x | × | 10 | + | x | x |
| = | 100 | + | 20 | x | + | x | x |
| 6 | x | = | 100 | + | 20 | x | + | x | x |