| ( | 48 | − | x | ) | ( | 50 | − | x | ) | = | ( | x | − | 18 | ) | x |
| Left side of the equation = | 48 | ( | 50 | − | x | ) | − | x | ( | 50 | − | x | ) |
| = | 48 | × | 50 | − | 48 | x | − | x | ( | 50 | − | x | ) |
| = | 2400 | − | 48 | x | − | x | ( | 50 | − | x | ) |
| = | 2400 | − | 48 | x | − | x | × | 50 | + | x | x |
| = | 2400 | − | 98 | x | + | x | x |
| 2400 | − | 98 | x | + | x | x | = | ( | x | − | 18 | ) | x |
| Right side of the equation = | x | x | − | 18 | x |
| 2400 | − | 98 | x | + | x | x | = | x | x | − | 18 | x |