| ( | 30 | + | 80 | − | x | ) | = | 3 2 | ( | 40 | + | x | ) |
| Left side of the equation = | 30 | + | 80 | − | x |
| = | 110 | − | x |
| 110 | − | x | = | 3 2 | ( | 40 | + | x | ) |
| Right side of the equation = | 3 2 | × | 40 | + | 3 2 | x |
| = | 60 | + | 3 2 | x |
| 110 | − | x | = | 60 | + | 3 2 | x |
| - | x | − | 3 2 | x | = | 60 | − | 110 |
| - | 5 2 | x | = | 60 | − | 110 |
| - | 5 2 | x | = | - | 50 |
| 50 | = | 5 2 | x |
5 2 | x | = | 50 |
| x | = | 50 | ÷ | 5 2 |
| = | 50 | × | 2 5 |
| = | 10 | × | 2 |
| x | = | 20 |