| ( | 10 | + | 2 | x | ) | ( | 100 | − | 4 | x | ) | = | 0 |
| Left side of the equation = | 10 | ( | 100 | − | 4 | x | ) | + | 2 | x | ( | 100 | − | 4 | x | ) |
| = | 10 | × | 100 | − | 10 | × | 4 | x | + | 2 | x | ( | 100 | − | 4 | x | ) |
| = | 1000 | − | 40 | x | + | 2 | x | ( | 100 | − | 4 | x | ) |
| = | 1000 | − | 40 | x | + | 2 | x | × | 100 | − | 2 | x | × | 4 | x |
| = | 1000 | − | 40 | x | + | 200 | x | − | 8 | x | x |
| = | 1000 | + | 160 | x | − | 8 | x | x |
| 1000 | + | 160 | x | − | 8 | x | x | = | 0 |