| 18 | × | 12 | − | ( | 18 | − | 2 | x | ) | ( | 12 | − | 2 | x | ) | = | 144 |
| 方程左边 = | 216 | − | ( | 18 | − | 2 | x | ) | ( | 12 | − | 2 | x | ) |
| 216 | − | ( | 18 | − | 2 | x | ) | ( | 12 | − | 2 | x | ) | = | 144 |
| 方程左边 = | 216 | − | 18 | ( | 12 | − | 2 | x | ) | + | 2 | x | ( | 12 | − | 2 | x | ) |
| = | 216 | − | 18 | × | 12 | + | 18 | × | 2 | x | + | 2 | x | ( | 12 | − | 2 | x | ) |
| = | 216 | − | 216 | + | 36 | x | + | 2 | x | ( | 12 | − | 2 | x | ) |
| = | 0 | + | 36 | x | + | 2 | x | ( | 12 | − | 2 | x | ) |
| = | 36 | x | + | 2 | x | × | 12 | − | 2 | x | × | 2 | x |
| = | 36 | x | + | 24 | x | − | 4 | x | x |
| = | 60 | x | − | 4 | x | x |
| 60 | x | − | 4 | x | x | = | 144 |