| ( | 1000 | − | 50 | x | ) | ( | 40 | + | 10 | x | ) | = | 24000 |
| Left side of the equation = | 1000 | ( | 40 | + | 10 | x | ) | − | 50 | x | ( | 40 | + | 10 | x | ) |
| = | 1000 | × | 40 | + | 1000 | × | 10 | x | − | 50 | x | ( | 40 | + | 10 | x | ) |
| = | 40000 | + | 10000 | x | − | 50 | x | ( | 40 | + | 10 | x | ) |
| = | 40000 | + | 10000 | x | − | 50 | x | × | 40 | − | 50 | x | × | 10 | x |
| = | 40000 | + | 10000 | x | − | 2000 | x | − | 500 | x | x |
| = | 40000 | + | 8000 | x | − | 500 | x | x |
| 40000 | + | 8000 | x | − | 500 | x | x | = | 24000 |