| 3 | ( | 12 | + | 7 20 | x | ) | = | 2 | ( | x | − | ( | 12 | + | 7 20 | x | ) | ) |
| Left side of the equation = | 3 | × | 12 | + | 3 | × | 7 20 | x |
| = | 36 | + | 21 20 | x |
| 36 | + | 21 20 | x | = | 2 | ( | x | − | ( | 12 | + | 7 20 | x | ) | ) |
| Right side of the equation = | 2 | x | − | 2 | ( | 12 | + | 7 20 | x | ) |
| = | 2 | x | − | 2 | × | 12 | − | 2 | × | 7 20 | x |
| = | 2 | x | − | 24 | − | 7 10 | x |
| = | 13 10 | x | − | 24 |
| 36 | + | 21 20 | x | = | 13 10 | x | − | 24 |
21 20 | x | − | 13 10 | x | = | - | 24 | − | 36 |
| - | 1 4 | x | = | - | 24 | − | 36 |
| - | 1 4 | x | = | - | 60 |
| 60 | = | 1 4 | x |
1 4 | x | = | 60 |
| x | = | 60 | ÷ | 1 4 |
| = | 60 | × | 4 |
| x | = | 240 |