| ( | x | − | 20 | ) | ( | 500 | − | 10 | ( | x | − | 20 | ) | ) | = | 2000 |
| Left side of the equation = | x | ( | 500 | − | 10 | ( | x | − | 20 | ) | ) | − | 20 | ( | 500 | − | 10 | ( | x | − | 20 | ) | ) |
| = | x | × | 500 | − | x | × | 10 | ( | x | − | 20 | ) | − | 20 | ( | 500 | − | 10 | ( | x | − | 20 | ) | ) |
| = | 500 | x | − | x | × | 10 | x | + | x | × | 10 | × | 20 | − | 20 | ( | 500 | − | 10 | ( | x | − | 20 | ) | ) |
| = | 500 | x | − | x | × | 10 | x | + | x | × | 200 | − | 20 | ( | 500 | − | 10 | ( | x | − | 20 | ) | ) |
| = | 700 | x | − | x | × | 10 | x | − | 20 | ( | 500 | − | 10 | ( | x | − | 20 | ) | ) |
| = | 700 | x | − | x | × | 10 | x | − | 20 | × | 500 | + | 20 | × | 10 | ( | x | − | 20 | ) |
| = | 700 | x | − | x | × | 10 | x | − | 10000 | + | 200 | ( | x | − | 20 | ) |
| = | 700 | x | − | x | × | 10 | x | − | 10000 | + | 200 | x | − | 200 | × | 20 |
| = | 700 | x | − | x | × | 10 | x | − | 10000 | + | 200 | x | − | 4000 |
| = | 900 | x | − | x | × | 10 | x | − | 14000 |
| 900 | x | − | x | × | 10 | x | − | 14000 | = | 2000 |