( | a | − | 20 | ) | ( | - | 2 | a | + | 80 | ) | = | 150 |
Left side of the equation = | a | ( | - | 2 | a | + | 80 | ) | − | 20 | ( | - | 2 | a | + | 80 | ) |
= | - | a | × | 2 | a | + | a | × | 80 | − | 20 | ( | - | 2 | a | + | 80 | ) |
= | - | a | × | 2 | a | + | 80 | a | + | 20 | × | 2 | a | − | 20 | × | 80 |
= | - | a | × | 2 | a | + | 80 | a | + | 40 | a | − | 1600 |
= | - | a | × | 2 | a | + | 120 | a | − | 1600 |
- | a | × | 2 | a | + | 120 | a | − | 1600 | = | 150 |