| ( | x | − | 120 | ) | ( | - | 2 | ÷ | 25 | × | x | + | 44 | ) | = | 2400 |
| 方程左边 = | x | ( | - | 2 | ÷ | 25 | × | x | + | 44 | ) | − | 120 | ( | - | 2 | ÷ | 25 | × | x | + | 44 | ) |
| = | - | x | × | 2 | ÷ | 25 | × | x | + | x | × | 44 | − | 120 | ( | - | 2 | ÷ | 25 | × | x | + | 44 | ) |
| = | - | x | × | 2 25 | x | + | x | × | 44 | − | 120 | ( | - | 2 | ÷ | 25 | × | x | + | 44 | ) |
| = | - | x | × | 2 25 | x | + | 44 | x | + | 120 | × | 2 | ÷ | 25 | × | x | − | 120 | × | 44 |
| = | - | x | × | 2 25 | x | + | 44 | x | + | 48 5 | x | − | 5280 |
| = | - | x | × | 2 25 | x | + | 268 5 | x | − | 5280 |
| - | x | × | 2 25 | x | + | 268 5 | x | − | 5280 | = | 2400 |