| 200 | x | ( | 3 20 | − | x | ) | = | 100 | x | ( | x | − | 3 20 | ) |
| Left side of the equation = | 200 | x | × | 3 20 | − | 200 | x | x |
| = | 30 | x | − | 200 | x | x |
| 30 | x | − | 200 | x | x | = | 100 | x | ( | x | − | 3 20 | ) |
| Right side of the equation = | 100 | x | x | − | 100 | x | × | 3 20 |
| = | 100 | x | x | − | 15 | x |
| 30 | x | − | 200 | x | x | = | 100 | x | x | − | 15 | x |
| x2= | 3 20 |