| ( | x | − | 50 | ) | x | ( | 2600 | − | 20 | x | ) | = | 24000 |
| Left side of the equation = | x | x | ( | 2600 | − | 20 | x | ) | − | 50 | x | ( | 2600 | − | 20 | x | ) |
| = | x | x | × | 2600 | − | x | x | × | 20 | x | − | 50 | x | ( | 2600 | − | 20 | x | ) |
| = | x | x | × | 2600 | − | x | x | × | 20 | x | − | 50 | x | × | 2600 | + | 50 | x |
| = | x | x | × | 2600 | − | x | x | × | 20 | x | − | 130000 | x | + | 1000 | x | x |
| x | x | × | 2600 | − | x | x | × | 20 | x | − | 130000 | x | + | 1000 | x | x | = | 24000 |