| x | ( | 20 | − | 4 | x | ) | + | x | ( | 12 | − | 4 | x | ) | + | 16 | x | x | = | 20 | × | 12 | ÷ | 6 |
| 方程左边 = | x | × | 20 | − | x | × | 4 | x | + | x | ( | 12 | − | 4 | x | ) | + | 16 | x | x |
| = | 20 | x | − | x | × | 4 | x | + | x | × | 12 | − | x | × | 4 | x | + | 16 | x |
| = | 32 | x | − | x | × | 4 | x | − | x | × | 4 | x | + | 16 | x | x |
| 32 | x | − | x | × | 4 | x | − | x | × | 4 | x | + | 16 | x | x | = | 20 | × | 12 | ÷ | 6 |
| 方程右边 = | 40 |
| 32 | x | − | x | × | 4 | x | − | x | × | 4 | x | + | 16 | x | x | = | 40 |