| 2 | ( | ( | 30 | − | x | ) | x | + | ( | 20 | − | x | ) | x | ) | = | 200 |
| Left side of the equation = | 2 | ( | 30 | − | x | ) | x | + | 2 | ( | 20 | − | x | ) | x |
| = | 2 | × | 30 | x | − | 2 | x | x | + | 2 | ( | 20 | − | x | ) | x |
| = | 60 | x | − | 2 | x | x | + | 2 | ( | 20 | − | x | ) | x |
| = | 60 | x | − | 2 | x | x | + | 2 | × | 20 | x | − | 2 | x | x |
| = | 60 | x | − | 2 | x | x | + | 40 | x | − | 2 | x | x |
| = | 100 | x | − | 2 | x | x | − | 2 | x | x |
| 100 | x | − | 2 | x | x | − | 2 | x | x | = | 200 |