| 9 | ( | 7 | x | + | 18 | ) | = | ( | 9 | x | − | 18 | ) | × | 7 |
| Left side of the equation = | 9 | × | 7 | x | + | 9 | × | 18 |
| = | 63 | x | + | 162 |
| 63 | x | + | 162 | = | ( | 9 | x | − | 18 | ) | × | 7 |
| Right side of the equation = | 9 | x | × | 7 | − | 18 | × | 7 |
| = | 63 | x | − | 126 |
| 63 | x | + | 162 | = | 63 | x | − | 126 |
| 63 | x | − | 63 | x | = | - | 126 | − | 162 |
| 0 | x | = | - | 126 | − | 162 |
| 0 | x | = | - | 288 |