( | 80 | − | 2 | t | ) | ( | 60 | − | t | ) | = | 300 |
Left side of the equation = | 80 | ( | 60 | − | t | ) | − | 2 | t | ( | 60 | − | t | ) |
= | 80 | × | 60 | − | 80 | t | − | 2 | t | ( | 60 | − | t | ) |
= | 4800 | − | 80 | t | − | 2 | t | ( | 60 | − | t | ) |
= | 4800 | − | 80 | t | − | 2 | t | × | 60 | + | 2 | t | t |
= | 4800 | − | 80 | t | − | 120 | t | + | 2 | t | t |
= | 4800 | − | 200 | t | + | 2 | t | t |
4800 | − | 200 | t | + | 2 | t | t | = | 300 |