| ( | x | − | 25 | ) | ( | - | 5 | x | + | 200 | ) | = | 130 |
| Left side of the equation = | x | ( | - | 5 | x | + | 200 | ) | − | 25 | ( | - | 5 | x | + | 200 | ) |
| = | - | x | × | 5 | x | + | x | × | 200 | − | 25 | ( | - | 5 | x | + | 200 | ) |
| = | - | x | × | 5 | x | + | 200 | x | + | 25 | × | 5 | x | − | 25 | × | 200 |
| = | - | x | × | 5 | x | + | 200 | x | + | 125 | x | − | 5000 |
| = | - | x | × | 5 | x | + | 325 | x | − | 5000 |
| - | x | × | 5 | x | + | 325 | x | − | 5000 | = | 130 |