| ( | 50 | + | x | − | ( | ( | 50 | + | x | ) | × | 20 100 | ) | ) | − | x | + | 10 100 | x | = | 100 |
| Left side of the equation = | ( | 50 | + | x | − | ( | ( | 50 | + | x | ) | × | 20 100 | ) | ) | − | 9 10 | x |
| ( | 50 | + | x | − | ( | ( | 50 | + | x | ) | × | 20 100 | ) | ) | − | 9 10 | x | = | 100 |
| Left side of the equation = | 50 | + | x | − | ( | ( | 50 | + | x | ) | × | 20 100 | ) | − | 9 10 | x |
| = | 50 | + | 1 10 | x | − | ( | ( | 50 | + | x | ) | × | 20 100 | ) |
| = | 50 | + | 1 10 | x | − | ( | 50 | + | x | ) | × | 20 100 |
| = | 50 | + | 1 10 | x | − | 50 | × | 20 100 | − | x | × | 20 100 |
| = | 50 | + | 1 10 | x | − | 10 | − | x | × | 20 100 |
| = | 40 | − | 1 10 | x |
| 40 | − | 1 10 | x | = | 100 |
| - | 1 10 | x | = | 100 | − | 40 |
| - | 1 10 | x | = | 60 |
| - | 60 | = | 1 10 | x |
1 10 | x | = | - | 60 |
| x | = | - | 60 | ÷ | 1 10 |
| = | - | 60 | × | 10 |
| x | = | - | 600 |