960 | = | ( | 6 | − | x | ) | ( | 200 | + | 20 | x | ) |
Right side of the equation = | 6 | ( | 200 | + | 20 | x | ) | − | x | ( | 200 | + | 20 | x | ) |
= | 6 | × | 200 | + | 6 | × | 20 | x | − | x | ( | 200 | + | 20 | x | ) |
= | 1200 | + | 120 | x | − | x | ( | 200 | + | 20 | x | ) |
= | 1200 | + | 120 | x | − | x | × | 200 | − | x | × | 20 | x |
= | 1200 | − | 80 | x | − | x | × | 20 | x |
960 | = | 1200 | − | 80 | x | − | x | × | 20 | x |