| ( | 10 | + | x | ) | x | ( | 500 | − | 10 | x | ) | = | 0 |
| Left side of the equation = | 10 | x | ( | 500 | − | 10 | x | ) | + | x | x | ( | 500 | − | 10 | x | ) |
| = | 10 | x | × | 500 | − | 10 | x | × | 10 | x | + | x | x | ( | 500 | − | 10 | x | ) |
| = | 5000 | x | − | 100 | x | x | + | x | x | ( | 500 | − | 10 | x | ) |
| = | 5000 | x | − | 100 | x | x | + | x | x | × | 500 | − | x | x | × | 10 | x |
| 5000 | x | − | 100 | x | x | + | x | x | × | 500 | − | x | x | × | 10 | x | = | 0 |