| 8 | ( | x | + | 3 | ) | + | 15 | = | 3 | ( | x | + | 3 | ) |
| Left side of the equation = | 8 | x | + | 8 | × | 3 | + | 15 |
| = | 8 | x | + | 24 | + | 15 |
| = | 8 | x | + | 39 |
| 8 | x | + | 39 | = | 3 | ( | x | + | 3 | ) |
| Right side of the equation = | 3 | x | + | 3 | × | 3 |
| = | 3 | x | + | 9 |
| 8 | x | + | 39 | = | 3 | x | + | 9 |
| 8 | x | − | 3 | x | = | 9 | − | 39 |
| 5 | x | = | 9 | − | 39 |
| 5 | x | = | - | 30 |
| x | = | - | 30 | ÷ | 5 |
| = | - | 30 | × | 1 5 |
| = | - | 6 | × | 1 |
| x | = | - | 6 |