| ( | x | − | 20 | ) | ( | - | 2 | x | + | 8 | ) | = | 150 |
| Left side of the equation = | x | ( | - | 2 | x | + | 8 | ) | − | 20 | ( | - | 2 | x | + | 8 | ) |
| = | - | x | × | 2 | x | + | x | × | 8 | − | 20 | ( | - | 2 | x | + | 8 | ) |
| = | - | x | × | 2 | x | + | 8 | x | + | 20 | × | 2 | x | − | 20 | × | 8 |
| = | - | x | × | 2 | x | + | 8 | x | + | 40 | x | − | 160 |
| = | - | x | × | 2 | x | + | 48 | x | − | 160 |
| - | x | × | 2 | x | + | 48 | x | − | 160 | = | 150 |