( | x | − | 20 | ) | ( | 600 | − | 10 | x | ) | = | 3840 |
Left side of the equation = | x | ( | 600 | − | 10 | x | ) | − | 20 | ( | 600 | − | 10 | x | ) |
= | x | × | 600 | − | x | × | 10 | x | − | 20 | ( | 600 | − | 10 | x | ) |
= | 600 | x | − | x | × | 10 | x | − | 20 | × | 600 | + | 20 | × | 10 | x |
= | 600 | x | − | x | × | 10 | x | − | 12000 | + | 200 | x |
= | 800 | x | − | x | × | 10 | x | − | 12000 |
800 | x | − | x | × | 10 | x | − | 12000 | = | 3840 |