| ( | 16 | − | 2 | x | ) | ( | 9 | − | x | ) | = | 112 |
| Left side of the equation = | 16 | ( | 9 | − | x | ) | − | 2 | x | ( | 9 | − | x | ) |
| = | 16 | × | 9 | − | 16 | x | − | 2 | x | ( | 9 | − | x | ) |
| = | 144 | − | 16 | x | − | 2 | x | ( | 9 | − | x | ) |
| = | 144 | − | 16 | x | − | 2 | x | × | 9 | + | 2 | x | x |
| = | 144 | − | 16 | x | − | 18 | x | + | 2 | x | x |
| = | 144 | − | 34 | x | + | 2 | x | x |
| 144 | − | 34 | x | + | 2 | x | x | = | 112 |