| ( | x | − | 2500 | ) | ( | 240 | − | 2 | x | ÷ | 25 | ) | = | 5000 |
| 方程左边 = | x | ( | 240 | − | 2 | x | ÷ | 25 | ) | − | 2500 | ( | 240 | − | 2 | x | ÷ | 25 | ) |
| = | x | × | 240 | − | x | × | 2 | x | ÷ | 25 | − | 2500 | ( | 240 | − | 2 | x | ÷ | 25 | ) |
| = | x | × | 240 | − | x | × | 2 25 | x | − | 2500 | ( | 240 | − | 2 | x | ÷ | 25 | ) |
| = | 240 | x | − | x | × | 2 25 | x | − | 2500 | × | 240 | + | 2500 | × | 2 | x | ÷ | 25 |
| = | 240 | x | − | x | × | 2 25 | x | − | 600000 | + | 200 | x |
| = | 440 | x | − | x | × | 2 25 | x | − | 600000 |
| 440 | x | − | x | × | 2 25 | x | − | 600000 | = | 5000 |