| ( | x | − | 2500 | ) | ( | 3000 | − | x | ) | = | 62500 |
| Left side of the equation = | x | ( | 3000 | − | x | ) | − | 2500 | ( | 3000 | − | x | ) |
| = | x | × | 3000 | − | x | x | − | 2500 | ( | 3000 | − | x | ) |
| = | 3000 | x | − | x | x | − | 2500 | × | 3000 | + | 2500 | x |
| = | 3000 | x | − | x | x | − | 7500000 | + | 2500 | x |
| = | 5500 | x | − | x | x | − | 7500000 |
| 5500 | x | − | x | x | − | 7500000 | = | 62500 |