| ( | x | − | 10 | ) | ( | 450 | − | 15 | x | ) | = | 1500 |
| Left side of the equation = | x | ( | 450 | − | 15 | x | ) | − | 10 | ( | 450 | − | 15 | x | ) |
| = | x | × | 450 | − | x | × | 15 | x | − | 10 | ( | 450 | − | 15 | x | ) |
| = | 450 | x | − | x | × | 15 | x | − | 10 | × | 450 | + | 10 | × | 15 | x |
| = | 450 | x | − | x | × | 15 | x | − | 4500 | + | 150 | x |
| = | 600 | x | − | x | × | 15 | x | − | 4500 |
| 600 | x | − | x | × | 15 | x | − | 4500 | = | 1500 |