| ( | 200 | + | 100 | x | ) | ( | 309 | − | 10 | x | ) | = | 0 |
| Left side of the equation = | 200 | ( | 309 | − | 10 | x | ) | + | 100 | x | ( | 309 | − | 10 | x | ) |
| = | 200 | × | 309 | − | 200 | × | 10 | x | + | 100 | x | ( | 309 | − | 10 | x | ) |
| = | 61800 | − | 2000 | x | + | 100 | x | ( | 309 | − | 10 | x | ) |
| = | 61800 | − | 2000 | x | + | 100 | x | × | 309 | − | 100 | x | × | 10 | x |
| = | 61800 | − | 2000 | x | + | 30900 | x | − | 1000 | x | x |
| = | 61800 | + | 28900 | x | − | 1000 | x | x |
| 61800 | + | 28900 | x | − | 1000 | x | x | = | 0 |
| x2= | 309 10 |