( | 800 | − | x | ) | ( | 4 | + | 1 50 | x | ) | = | 4200 |
Left side of the equation = | 800 | ( | 4 | + | 1 50 | x | ) | − | x | ( | 4 | + | 1 50 | x | ) |
= | 800 | × | 4 | + | 800 | × | 1 50 | x | − | x | ( | 4 | + | 1 50 | x | ) |
= | 3200 | + | 16 | x | − | x | ( | 4 | + | 1 50 | x | ) |
= | 3200 | + | 16 | x | − | x | × | 4 | − | x | × | 1 50 | x |
= | 3200 | + | 12 | x | − | x | × | 1 50 | x |
3200 | + | 12 | x | − | x | × | 1 50 | x | = | 4200 |