| ( | 60 | − | x | − | 30 | ) | ( | 10 | x | + | 100 | ) | = | 0 |
| Left side of the equation = | 60 | ( | 10 | x | + | 100 | ) | − | x | ( | 10 | x | + | 100 | ) | − | 30 | ( | 10 | x | + | 100 | ) |
| = | 60 | × | 10 | x | + | 60 | × | 100 | − | x | ( | 10 | x | + | 100 | ) | − | 30 | ( | 10 | x | + | 100 | ) |
| = | 600 | x | + | 6000 | − | x | ( | 10 | x | + | 100 | ) | − | 30 | ( | 10 | x | + | 100 | ) |
| = | 600 | x | + | 6000 | − | x | × | 10 | x | − | x | × | 100 | − | 30 | ( | 10 | x | + | 100 | ) |
| = | 500 | x | + | 6000 | − | x | × | 10 | x | − | 30 | ( | 10 | x | + | 100 | ) |
| = | 500 | x | + | 6000 | − | x | × | 10 | x | − | 30 | × | 10 | x | − | 30 | × | 100 |
| = | 500 | x | + | 6000 | − | x | × | 10 | x | − | 300 | x | − | 3000 |
| = | 200 | x | + | 3000 | − | x | × | 10 | x |
| 200 | x | + | 3000 | − | x | × | 10 | x | = | 0 |