| - | 10 | ( | x | − | 9 | ) | − | 5 | ( | x | − | 8 | ) | + | 7 | = | 2 |
| Left side of the equation = | - | 10 | x | + | 10 | × | 9 | − | 5 | ( | x | − | 8 | ) | + | 7 |
| = | - | 10 | x | + | 90 | − | 5 | ( | x | − | 8 | ) | + | 7 |
| = | - | 10 | x | + | 97 | − | 5 | ( | x | − | 8 | ) |
| = | - | 10 | x | + | 97 | − | 5 | x | + | 5 | × | 8 |
| = | - | 10 | x | + | 97 | − | 5 | x | + | 40 |
| = | - | 15 | x | + | 137 |
| - | 15 | x | + | 137 | = | 2 |
| - | 15 | x | = | 2 | − | 137 |
| - | 15 | x | = | - | 135 |
| 135 | = | 15 | x |
| 15 | x | = | 135 |
| x | = | 135 | ÷ | 15 |
| = | 135 | × | 1 15 |
| = | 9 | × | 1 |
| x | = | 9 |