| ( | 200 | + | 180 | x | ) | ( | 400 | − | 50 | x | ) | = | 0 |
| Left side of the equation = | 200 | ( | 400 | − | 50 | x | ) | + | 180 | x | ( | 400 | − | 50 | x | ) |
| = | 200 | × | 400 | − | 200 | × | 50 | x | + | 180 | x | ( | 400 | − | 50 | x | ) |
| = | 80000 | − | 10000 | x | + | 180 | x | ( | 400 | − | 50 | x | ) |
| = | 80000 | − | 10000 | x | + | 180 | x | × | 400 | − | 180 | x | × | 50 | x |
| = | 80000 | − | 10000 | x | + | 72000 | x | − | 9000 | x | x |
| = | 80000 | + | 62000 | x | − | 9000 | x | x |
| 80000 | + | 62000 | x | − | 9000 | x | x | = | 0 |
| x1= | - | 10 9 |
| x2=8 |