| ( | 21 5 | − | x | ) | ÷ | x | = | 87 20 |
| Multiply both sides of the equation by: | x |
| ( | 21 5 | − | x | ) | = | 87 20 | x |
21 5 | − | x | = | 87 20 | x |
| - | x | − | 87 20 | x | = | - | 21 5 |
| - | 107 20 | x | = | - | 21 5 |
21 5 | = | 107 20 | x |
107 20 | x | = | 21 5 |
| x | = | 21 5 | ÷ | 107 20 |
| = | 21 5 | × | 20 107 |
| = | 21 | × | 4 107 |
| x | = | 84 107 |
| x | = | 0.785047 |