500 | ( | a | − | 35 | ) | + | 20 | a | ( | a | − | 35 | ) | = | 8400 |
Left side of the equation = | 500 | a | − | 500 | × | 35 | + | 20 | a | ( | a | − | 35 | ) |
= | 500 | a | − | 17500 | + | 20 | a | ( | a | − | 35 | ) |
= | 500 | a | − | 17500 | + | 20 | a | a | − | 20 | a | × | 35 |
= | 500 | a | − | 17500 | + | 20 | a | a | − | 700 | a |
= | - | 200 | a | − | 17500 | + | 20 | a | a |
- | 200 | a | − | 17500 | + | 20 | a | a | = | 8400 |