| - | 7 | ( | 9 | x | + | 1 | ) | + | 14 | ( | 7 | x | − | 18 | ) | − | 1 | = | - | 15 |
| Left side of the equation = | - | 7 | × | 9 | x | − | 7 | × | 1 | + | 14 | ( | 7 | x | − | 18 | ) | − | 1 |
| = | - | 63 | x | − | 7 | + | 14 | ( | 7 | x | − | 18 | ) | − | 1 |
| = | - | 63 | x | − | 8 | + | 14 | ( | 7 | x | − | 18 | ) |
| = | - | 63 | x | − | 8 | + | 14 | × | 7 | x | − | 14 | × | 18 |
| = | - | 63 | x | − | 8 | + | 98 | x | − | 252 |
| = | 35 | x | − | 260 |
| 35 | x | − | 260 | = | - | 15 |
| 35 | x | = | - | 15 | + | 260 |
| 35 | x | = | 245 |
| x | = | 245 | ÷ | 35 |
| = | 245 | × | 1 35 |
| = | 7 | × | 1 |
| x | = | 7 |