| ( | 100 | y | − | 5 | y | ) | − | ( | 400 | + | 20 | y | ) | = | 0 |
| Left side of the equation = | 100 | y | − | 5 | y | − | ( | 400 | + | 20 | y | ) |
| = | 95 | y | − | ( | 400 | + | 20 | y | ) |
| = | 95 | y | − | 400 | − | 20 | y |
| = | 75 | y | − | 400 |
| 75 | y | − | 400 | = | 0 |
| 75 | y | = | 0 | + | 400 |
| 75 | y | = | 400 |
| y | = | 400 | ÷ | 75 |
| = | 400 | × | 1 75 |
| = | 16 | × | 1 3 |
| y | = | 16 3 |
| y | = | 5.333333 |