| ( | 12 | x | − | 8 | − | 10 | x | ) | + | ( | 8 | x | + | 11 | + | 7 | x | ) | = | 20 |
| Left side of the equation = | 12 | x | − | 8 | − | 10 | x | + | ( | 8 | x | + | 11 | + | 7 | x | ) |
| = | 2 | x | − | 8 | + | ( | 8 | x | + | 11 | + | 7 | x | ) |
| = | 2 | x | − | 8 | + | 8 | x | + | 11 | + | 7 | x |
| = | 17 | x | + | 3 |
| 17 | x | + | 3 | = | 20 |
| 17 | x | = | 20 | − | 3 |
| 17 | x | = | 17 |
| x | = | 17 | ÷ | 17 |
| = | 17 | × | 1 17 |
| = | 1 | × | 1 |
| x | = | 1 |