| ( | 5 4 | y | − | 5 | ) | ÷ | ( | y | − | 10 | ) | = | 4 | ÷ | 5 |
| Multiply both sides of the equation by: | ( | y | − | 10 | ) |
| ( | 5 4 | y | − | 5 | ) | = | 4 | ÷ | 5 | × | ( | y | − | 10 | ) |
5 4 | y | − | 5 | = | 4 | ÷ | 5 | × | ( | y | − | 10 | ) |
5 4 | y | − | 5 | = | 4 | ÷ | 5 | × | y | − | 4 | ÷ | 5 | × | 10 |
5 4 | y | − | 5 | = | 4 5 | y | − | 8 |
5 4 | y | − | 4 5 | y | = | - | 8 | + | 5 |
9 20 | y | = | - | 8 | + | 5 |
9 20 | y | = | - | 3 |
| y | = | - | 3 | ÷ | 9 20 |
| = | - | 3 | × | 20 9 |
| = | - | 1 | × | 20 3 |
| y | = | - | 20 3 |
| y | = | - 6.666667 |