| 1 | − | 2 | ( | x | + | 3 | ) | = | 3 | x | − | 7 | x | + | 7 |
| Left side of the equation = | 1 | − | 2 | x | − | 2 | × | 3 |
| = | 1 | − | 2 | x | − | 6 |
| = | - | 5 | − | 2 | x |
| - | 5 | − | 2 | x | = | 3 | x | − | 7 | x | + | 7 |
| Right side of the equation = | - | 4 | x | + | 7 |
| - | 5 | − | 2 | x | = | - | 4 | x | + | 7 |
| - | 2 | x | + | 4 | x | = | 7 | + | 5 |
| 2 | x | = | 7 | + | 5 |
| 2 | x | = | 12 |
| x | = | 12 | ÷ | 2 |
| = | 12 | × | 1 2 |
| = | 6 | × | 1 |
| x | = | 6 |