| ( | x | − | 12 | ) | ( | x | − | 99 | ÷ | 8 | ) | − | 9 | = | 0 |
| Left side of the equation = | x | ( | x | − | 99 | ÷ | 8 | ) | − | 12 | ( | x | − | 99 | ÷ | 8 | ) | − | 9 |
| = | x | x | − | x | × | 99 | ÷ | 8 | − | 12 | ( | x | − | 99 | ÷ | 8 | ) | − | 9 |
| = | x | x | − | x | × | 99 8 | − | 12 | ( | x | − | 99 | ÷ | 8 | ) | − | 9 |
| = | x | x | − | 99 8 | x | − | 12 | x | + | 12 | × | 99 | ÷ | 8 | − | 9 |
| = | x | x | − | 99 8 | x | − | 12 | x | + | 297 2 | − | 9 |
| = | x | x | − | 195 8 | x | + | 279 2 |
| x | x | − | 195 8 | x | + | 279 2 | = | 0 |