| 6 | ( | x | + | 1 | ) | = | 9 | ( | x | − | 1 | ) |
| Left side of the equation = | 6 | x | + | 6 | × | 1 |
| = | 6 | x | + | 6 |
| 6 | x | + | 6 | = | 9 | ( | x | − | 1 | ) |
| Right side of the equation = | 9 | x | − | 9 | × | 1 |
| = | 9 | x | − | 9 |
| 6 | x | + | 6 | = | 9 | x | − | 9 |
| 6 | x | − | 9 | x | = | - | 9 | − | 6 |
| - | 3 | x | = | - | 9 | − | 6 |
| - | 3 | x | = | - | 15 |
| 15 | = | 3 | x |
| 3 | x | = | 15 |
| x | = | 15 | ÷ | 3 |
| = | 15 | × | 1 3 |
| = | 5 | × | 1 |
| x | = | 5 |