| ( | 8 | − | 2 | x | ) | ( | 5 | − | 2 | x | ) | = | 18 |
| Left side of the equation = | 8 | ( | 5 | − | 2 | x | ) | − | 2 | x | ( | 5 | − | 2 | x | ) |
| = | 8 | × | 5 | − | 8 | × | 2 | x | − | 2 | x | ( | 5 | − | 2 | x | ) |
| = | 40 | − | 16 | x | − | 2 | x | ( | 5 | − | 2 | x | ) |
| = | 40 | − | 16 | x | − | 2 | x | × | 5 | + | 2 | x | × | 2 | x |
| = | 40 | − | 16 | x | − | 10 | x | + | 4 | x | x |
| = | 40 | − | 26 | x | + | 4 | x | x |
| 40 | − | 26 | x | + | 4 | x | x | = | 18 |
| x2= | 11 2 |