| ( | 25 | − | x | ) | x | ( | 20 | + | 2 | x | ) | = | 600 |
| Left side of the equation = | 25 | x | ( | 20 | + | 2 | x | ) | − | x | x | ( | 20 | + | 2 | x | ) |
| = | 25 | x | × | 20 | + | 25 | x | × | 2 | x | − | x | x | ( | 20 | + | 2 | x | ) |
| = | 500 | x | + | 50 | x | x | − | x | x | ( | 20 | + | 2 | x | ) |
| = | 500 | x | + | 50 | x | x | − | x | x | × | 20 | − | x | x | × | 2 | x |
| 500 | x | + | 50 | x | x | − | x | x | × | 20 | − | x | x | × | 2 | x | = | 600 |