| 75 | ÷ | X | = | 105 | ÷ | ( | X | + | 3 | ) |
| Multiply both sides of the equation by: | X | , | ( | X | + | 3 | ) |
| 75 | ( | X | + | 3 | ) | = | 105 | X |
| 75 | X | + | 75 | × | 3 | = | 105 | X |
| 75 | X | + | 225 | = | 105 | X |
| 75 | X | − | 105 | X | = | - | 225 |
| - | 30 | X | = | - | 225 |
| 225 | = | 30 | X |
| 30 | X | = | 225 |
| X | = | 225 | ÷ | 30 |
| = | 225 | × | 1 30 |
| = | 15 | × | 1 2 |
| X | = | 15 2 |
| X | = | 7.5 |