| ( | 40 | − | x | ) | ( | 60 | + | 2 | x | ) | − | 500 | = | 1950 |
| 方程左边 = | 40 | ( | 60 | + | 2 | x | ) | − | x | ( | 60 | + | 2 | x | ) | − | 500 |
| = | 40 | × | 60 | + | 40 | × | 2 | x | − | x | ( | 60 | + | 2 | x | ) | − | 500 |
| = | 2400 | + | 80 | x | − | x | ( | 60 | + | 2 | x | ) | − | 500 |
| = | 1900 | + | 80 | x | − | x | ( | 60 | + | 2 | x | ) |
| = | 1900 | + | 80 | x | − | x | × | 60 | − | x | × | 2 | x |
| = | 1900 | + | 20 | x | − | x | × | 2 | x |
| 1900 | + | 20 | x | − | x | × | 2 | x | = | 1950 |