| 20 | ( | x | + | 6 | ) | = | 12 | ( | x | + | 6 | ) | + | 12 | x |
| Left side of the equation = | 20 | x | + | 20 | × | 6 |
| = | 20 | x | + | 120 |
| 20 | x | + | 120 | = | 12 | ( | x | + | 6 | ) | + | 12 | x |
| Right side of the equation = | 12 | x | + | 12 | × | 6 | + | 12 | x |
| = | 12 | x | + | 72 | + | 12 | x |
| = | 24 | x | + | 72 |
| 20 | x | + | 120 | = | 24 | x | + | 72 |
| 20 | x | − | 24 | x | = | 72 | − | 120 |
| - | 4 | x | = | 72 | − | 120 |
| - | 4 | x | = | - | 48 |
| 48 | = | 4 | x |
| 4 | x | = | 48 |
| x | = | 48 | ÷ | 4 |
| = | 48 | × | 1 4 |
| = | 12 | × | 1 |
| x | = | 12 |