| - | 7 | + | 7 | ( | 9 | − | 2 | ( | 1 | + | x | ) | ) | = | 11 | ( | - | x | + | 9 | ) |
| Left side of the equation = | - | 7 | + | 7 | × | 9 | − | 7 | × | 2 | ( | 1 | + | x | ) |
| = | - | 7 | + | 63 | − | 14 | ( | 1 | + | x | ) |
| = | 56 | − | 14 | ( | 1 | + | x | ) |
| = | 56 | − | 14 | × | 1 | − | 14 | x |
| = | 56 | − | 14 | − | 14 | x |
| = | 42 | − | 14 | x |
| 42 | − | 14 | x | = | 11 | ( | - | x | + | 9 | ) |
| Right side of the equation = | - | 11 | x | + | 11 | × | 9 |
| = | - | 11 | x | + | 99 |
| 42 | − | 14 | x | = | - | 11 | x | + | 99 |
| - | 14 | x | + | 11 | x | = | 99 | − | 42 |
| - | 3 | x | = | 99 | − | 42 |
| - | 3 | x | = | 57 |
| - | 57 | = | 3 | x |
| 3 | x | = | - | 57 |
| x | = | - | 57 | ÷ | 3 |
| = | - | 57 | × | 1 3 |
| = | - | 19 | × | 1 |
| x | = | - | 19 |