| 20 | ( | 30 | + | x | ) | ÷ | 60 | = | 40 | x | ÷ | 80 |
| Left side of the equation = | 1 3 | ( | 30 | + | x | ) |
1 3 | ( | 30 | + | x | ) | = | 40 | x | ÷ | 80 |
| Left side of the equation = | 1 3 | × | 30 | + | 1 3 | x |
| = | 10 | + | 1 3 | x |
| 10 | + | 1 3 | x | = | 40 | x | ÷ | 80 |
| Right side of the equation = | 1 2 | x |
| 10 | + | 1 3 | x | = | 1 2 | x |
1 3 | x | − | 1 2 | x | = | - | 10 |
| - | 1 6 | x | = | - | 10 |
| 10 | = | 1 6 | x |
1 6 | x | = | 10 |
| x | = | 10 | ÷ | 1 6 |
| = | 10 | × | 6 |
| x | = | 60 |