| ( | 12 | − | 2 | x | ) | ( | 30 | − | 2 | x | ) | ÷ | 2 | = | 104 |
| Left side of the equation = | 12 | ( | 30 | − | 2 | x | ) | × | 1 2 | − | 2 | x | ( | 30 | − | 2 | x | ) | × | 1 2 |
| = | 6 | ( | 30 | − | 2 | x | ) | − | 1 | x | ( | 30 | − | 2 | x | ) |
| = | 6 | × | 30 | − | 6 | × | 2 | x | − | 1 | x | ( | 30 | − | 2 | x | ) |
| = | 180 | − | 12 | x | − | 1 | x | ( | 30 | − | 2 | x | ) |
| = | 180 | − | 12 | x | − | 1 | x | × | 30 | + | 1 | x | × | 2 | x |
| = | 180 | − | 12 | x | − | 30 | x | + | 2 | x | x |
| = | 180 | − | 42 | x | + | 2 | x | x |
| 180 | − | 42 | x | + | 2 | x | x | = | 104 |