| ( | 500 | + | 5 | x | ) | ( | 15 | − | x | ) | = | 4250 |
| Left side of the equation = | 500 | ( | 15 | − | x | ) | + | 5 | x | ( | 15 | − | x | ) |
| = | 500 | × | 15 | − | 500 | x | + | 5 | x | ( | 15 | − | x | ) |
| = | 7500 | − | 500 | x | + | 5 | x | ( | 15 | − | x | ) |
| = | 7500 | − | 500 | x | + | 5 | x | × | 15 | − | 5 | x | x |
| = | 7500 | − | 500 | x | + | 75 | x | − | 5 | x | x |
| = | 7500 | − | 425 | x | − | 5 | x | x |
| 7500 | − | 425 | x | − | 5 | x | x | = | 4250 |