| ( | x | − | 75 | ) | ( | 525 | − | 5 | x | ) | = | 1080 |
| Left side of the equation = | x | ( | 525 | − | 5 | x | ) | − | 75 | ( | 525 | − | 5 | x | ) |
| = | x | × | 525 | − | x | × | 5 | x | − | 75 | ( | 525 | − | 5 | x | ) |
| = | 525 | x | − | x | × | 5 | x | − | 75 | × | 525 | + | 75 | × | 5 | x |
| = | 525 | x | − | x | × | 5 | x | − | 39375 | + | 375 | x |
| = | 900 | x | − | x | × | 5 | x | − | 39375 |
| 900 | x | − | x | × | 5 | x | − | 39375 | = | 1080 |