| 19 | ( | x | − | 8 | ) | + | 3 | ( | - | 3 | x | + | 9 | ) | − | 4 | = | - | 9 |
| Left side of the equation = | 19 | x | − | 19 | × | 8 | + | 3 | ( | - | 3 | x | + | 9 | ) | − | 4 |
| = | 19 | x | − | 152 | + | 3 | ( | - | 3 | x | + | 9 | ) | − | 4 |
| = | 19 | x | − | 156 | + | 3 | ( | - | 3 | x | + | 9 | ) |
| = | 19 | x | − | 156 | − | 3 | × | 3 | x | + | 3 | × | 9 |
| = | 19 | x | − | 156 | − | 9 | x | + | 27 |
| = | 10 | x | − | 129 |
| 10 | x | − | 129 | = | - | 9 |
| 10 | x | = | - | 9 | + | 129 |
| 10 | x | = | 120 |
| x | = | 120 | ÷ | 10 |
| = | 120 | × | 1 10 |
| = | 12 | × | 1 |
| x | = | 12 |