| ( | 500 | − | 50 | x | ) | ( | 40 | + | 10 | x | ) | = | 24000 |
| Left side of the equation = | 500 | ( | 40 | + | 10 | x | ) | − | 50 | x | ( | 40 | + | 10 | x | ) |
| = | 500 | × | 40 | + | 500 | × | 10 | x | − | 50 | x | ( | 40 | + | 10 | x | ) |
| = | 20000 | + | 5000 | x | − | 50 | x | ( | 40 | + | 10 | x | ) |
| = | 20000 | + | 5000 | x | − | 50 | x | × | 40 | − | 50 | x | × | 10 | x |
| = | 20000 | + | 5000 | x | − | 2000 | x | − | 500 | x | x |
| = | 20000 | + | 3000 | x | − | 500 | x | x |
| 20000 | + | 3000 | x | − | 500 | x | x | = | 24000 |