( | 1 | + | n | ) | ( | 600 | − | 20 | n | ) | = | 5000 |
Left side of the equation = | 1 | ( | 600 | − | 20 | n | ) | + | n | ( | 600 | − | 20 | n | ) |
= | 1 | × | 600 | − | 1 | × | 20 | n | + | n | ( | 600 | − | 20 | n | ) |
= | 600 | − | 20 | n | + | n | ( | 600 | − | 20 | n | ) |
= | 600 | − | 20 | n | + | n | × | 600 | − | n | × | 20 | n |
= | 600 | + | 580 | n | − | n | × | 20 | n |
600 | + | 580 | n | − | n | × | 20 | n | = | 5000 |