| 3 | x | − | ( | 4 | x | + | 1 | ) | = | 2 | ( | 2 | x | + | 7 | ) |
| Left side of the equation = | 3 | x | − | 4 | x | − | 1 |
| = | - | 1 | x | − | 1 |
| - | 1 | x | − | 1 | = | 2 | ( | 2 | x | + | 7 | ) |
| Right side of the equation = | 2 | × | 2 | x | + | 2 | × | 7 |
| = | 4 | x | + | 14 |
| - | 1 | x | − | 1 | = | 4 | x | + | 14 |
| - | 1 | x | − | 4 | x | = | 14 | + | 1 |
| - | 5 | x | = | 14 | + | 1 |
| - | 5 | x | = | 15 |
| - | 15 | = | 5 | x |
| 5 | x | = | - | 15 |
| x | = | - | 15 | ÷ | 5 |
| = | - | 15 | × | 1 5 |
| = | - | 3 | × | 1 |
| x | = | - | 3 |