| ( | 27 | − | 4 | x | ) | ( | 12 | − | 3 | x | ) | = | 27 | × | 8 |
| 方程左边 = | 27 | ( | 12 | − | 3 | x | ) | − | 4 | x | ( | 12 | − | 3 | x | ) |
| = | 27 | × | 12 | − | 27 | × | 3 | x | − | 4 | x | ( | 12 | − | 3 | x | ) |
| = | 324 | − | 81 | x | − | 4 | x | ( | 12 | − | 3 | x | ) |
| = | 324 | − | 81 | x | − | 4 | x | × | 12 | + | 4 | x | × | 3 | x |
| = | 324 | − | 81 | x | − | 48 | x | + | 12 | x | x |
| = | 324 | − | 129 | x | + | 12 | x | x |
| 324 | − | 129 | x | + | 12 | x | x | = | 27 | × | 8 |
| 方程右边 = | 216 |
| 324 | − | 129 | x | + | 12 | x | x | = | 216 |