( | 15 | - | y | ) | ( | 500 | + | 5 | y | ) | = | 4250 |
Left side of the equation = | 15 | ( | 500 | + | 5 | y | ) | - | y | ( | 500 | + | 5 | y | ) |
= | 15 | × | 500 | + | 15 | × | 5 | y | - | y | ( | 500 | + | 5 | y | ) |
= | 7500 | + | 75 | y | - | y | ( | 500 | + | 5 | y | ) |
= | 7500 | + | 75 | y | - | y | × | 500 | - | y | × | 5 | y |
= | 7500 | - | 425 | y | - | y | × | 5 | y |
7500 | - | 425 | y | - | y | × | 5 | y | = | 4250 |