| ( | 3 | − | x | ) | ( | - | 45 | − | 2 | x | ) | = | 9 |
| Left side of the equation = | 3 | ( | - | 45 | − | 2 | x | ) | − | x | ( | - | 45 | − | 2 | x | ) |
| = | - | 3 | × | 45 | − | 3 | × | 2 | x | − | x | ( | - | 45 | − | 2 | x | ) |
| = | - | 135 | − | 6 | x | − | x | ( | - | 45 | − | 2 | x | ) |
| = | - | 135 | − | 6 | x | + | x | × | 45 | + | x | × | 2 | x |
| = | - | 135 | + | 39 | x | + | x | × | 2 | x |
| - | 135 | + | 39 | x | + | x | × | 2 | x | = | 9 |