| ( | 300 | − | 30 | x | ) | ( | 500 | + | 1000 | x | ) | = | 0 |
| Left side of the equation = | 300 | ( | 500 | + | 1000 | x | ) | − | 30 | x | ( | 500 | + | 1000 | x | ) |
| = | 300 | × | 500 | + | 300 | × | 1000 | x | − | 30 | x | ( | 500 | + | 1000 | x | ) |
| = | 150000 | + | 300000 | x | − | 30 | x | ( | 500 | + | 1000 | x | ) |
| = | 150000 | + | 300000 | x | − | 30 | x | × | 500 | − | 30 | x | × | 1000 | x |
| = | 150000 | + | 300000 | x | − | 15000 | x | − | 30000 | x | x |
| = | 150000 | + | 285000 | x | − | 30000 | x | x |
| 150000 | + | 285000 | x | − | 30000 | x | x | = | 0 |
| x1= | - | 1 2 |
| x2=10 |