| ( | 162 | − | 2 | x | ) | ( | 60 | − | 4 | x | ) | = | 9600 |
| 方程左边 = | 162 | ( | 60 | − | 4 | x | ) | − | 2 | x | ( | 60 | − | 4 | x | ) |
| = | 162 | × | 60 | − | 162 | × | 4 | x | − | 2 | x | ( | 60 | − | 4 | x | ) |
| = | 9720 | − | 648 | x | − | 2 | x | ( | 60 | − | 4 | x | ) |
| = | 9720 | − | 648 | x | − | 2 | x | × | 60 | + | 2 | x | × | 4 | x |
| = | 9720 | − | 648 | x | − | 120 | x | + | 8 | x | x |
| = | 9720 | − | 768 | x | + | 8 | x | x |
| 9720 | − | 768 | x | + | 8 | x | x | = | 9600 |