| ( | 10 | − | 2 | x | ) | ( | 8 | − | 2 | x | ) | = | 64 |
| Left side of the equation = | 10 | ( | 8 | − | 2 | x | ) | − | 2 | x | ( | 8 | − | 2 | x | ) |
| = | 10 | × | 8 | − | 10 | × | 2 | x | − | 2 | x | ( | 8 | − | 2 | x | ) |
| = | 80 | − | 20 | x | − | 2 | x | ( | 8 | − | 2 | x | ) |
| = | 80 | − | 20 | x | − | 2 | x | × | 8 | + | 2 | x | × | 2 | x |
| = | 80 | − | 20 | x | − | 16 | x | + | 4 | x | x |
| = | 80 | − | 36 | x | + | 4 | x | x |
| 80 | − | 36 | x | + | 4 | x | x | = | 64 |