| ( | 10 | + | x | ) | ( | 1000 | − | 100 | x | ) | = | 9600 |
| Left side of the equation = | 10 | ( | 1000 | − | 100 | x | ) | + | x | ( | 1000 | − | 100 | x | ) |
| = | 10 | × | 1000 | − | 10 | × | 100 | x | + | x | ( | 1000 | − | 100 | x | ) |
| = | 10000 | − | 1000 | x | + | x | ( | 1000 | − | 100 | x | ) |
| = | 10000 | − | 1000 | x | + | x | × | 1000 | − | x | × | 100 | x |
| = | 10000 | − | 0 | x | − | x | × | 100 | x |
| 10000 | − | 0 | x | − | x | × | 100 | x | = | 9600 |