| ( | x | − | 190 | ) | ( | - | 2 | x | + | 418 | ) | = | 280 |
| Left side of the equation = | x | ( | - | 2 | x | + | 418 | ) | − | 190 | ( | - | 2 | x | + | 418 | ) |
| = | - | x | × | 2 | x | + | x | × | 418 | − | 190 | ( | - | 2 | x | + | 418 | ) |
| = | - | x | × | 2 | x | + | 418 | x | + | 190 | × | 2 | x | − | 190 | × | 418 |
| = | - | x | × | 2 | x | + | 418 | x | + | 380 | x | − | 79420 |
| = | - | x | × | 2 | x | + | 798 | x | − | 79420 |
| - | x | × | 2 | x | + | 798 | x | − | 79420 | = | 280 |