| ( | 200 | − | 10 | x | ) | ( | x | − | 8 | ) | = | 0 |
| Left side of the equation = | 200 | ( | x | − | 8 | ) | − | 10 | x | ( | x | − | 8 | ) |
| = | 200 | x | − | 200 | × | 8 | − | 10 | x | ( | x | − | 8 | ) |
| = | 200 | x | − | 1600 | − | 10 | x | ( | x | − | 8 | ) |
| = | 200 | x | − | 1600 | − | 10 | x | x | + | 10 | x | × | 8 |
| = | 200 | x | − | 1600 | − | 10 | x | x | + | 80 | x |
| = | 280 | x | − | 1600 | − | 10 | x | x |
| 280 | x | − | 1600 | − | 10 | x | x | = | 0 |