( | 40 | − | 30 | + | x | ) | ( | 80 | + | 2 | x | ) | = | 1200 |
Left side of the equation = | 40 | ( | 80 | + | 2 | x | ) | − | 30 | ( | 80 | + | 2 | x | ) | + | x | ( | 80 | + | 2 | x | ) |
= | 40 | × | 80 | + | 40 | × | 2 | x | − | 30 | ( | 80 | + | 2 | x | ) | + | x | ( | 80 | + | 2 | x | ) |
= | 3200 | + | 80 | x | − | 30 | ( | 80 | + | 2 | x | ) | + | x | ( | 80 | + | 2 | x | ) |
= | 3200 | + | 80 | x | − | 30 | × | 80 | − | 30 | × | 2 | x | + | x | ( | 80 | + | 2 | x | ) |
= | 3200 | + | 80 | x | − | 2400 | − | 60 | x | + | x | ( | 80 | + | 2 | x | ) |
= | 800 | + | 20 | x | + | x | ( | 80 | + | 2 | x | ) |
= | 800 | + | 20 | x | + | x | × | 80 | + | x | × | 2 | x |
= | 800 | + | 100 | x | + | x | × | 2 | x |
800 | + | 100 | x | + | x | × | 2 | x | = | 1200 |