| x | − | ( | 1 | ÷ | 5 | × | x | + | 20 | ) | − | ( | 1 | ÷ | 5 | × | x | + | 20 | ) | = | 20 |
| Left side of the equation = | x | − | 1 | ÷ | 5 | × | x | − | 20 | − | ( | 1 | ÷ | 5 | × | x | + | 20 | ) |
| = | x | − | 1 5 | x | − | 20 | − | ( | 1 | ÷ | 5 | × | x | + | 20 | ) |
| = | 4 5 | x | − | 20 | − | ( | 1 | ÷ | 5 | × | x | + | 20 | ) |
| = | 4 5 | x | − | 20 | − | 1 | ÷ | 5 | × | x | − | 20 |
| = | 4 5 | x | − | 20 | − | 1 5 | x | − | 20 |
| = | 3 5 | x | − | 40 |
3 5 | x | − | 40 | = | 20 |
3 5 | x | = | 20 | + | 40 |
3 5 | x | = | 60 |
| x | = | 60 | ÷ | 3 5 |
| = | 60 | × | 5 3 |
| = | 20 | × | 5 |
| x | = | 100 |