| 3 | = | 100 | ( | 300 | − | X | ) | ÷ | ( | 300 | × | 500 | ÷ | 100 | ) |
| Multiply both sides of the equation by: | ( | 300 | × | 500 | ÷ | 100 | ) |
| 3 | ( | 300 | × | 500 | ÷ | 100 | ) | = | 100 | ( | 300 | − | X | ) |
| 3 | × | 300 | × | 500 | ÷ | 100 | = | 100 | ( | 300 | − | X | ) |
| 3 | × | 300 | × | 500 | ÷ | 100 | = | 100 | × | 300 | − | 100 | X |
| 4500 | = | 30000 | − | 100 | X |
| 100 | X | = | 30000 | − | 4500 |
| 100 | X | = | 25500 |
| X | = | 25500 | ÷ | 100 |
| = | 25500 | × | 1 100 |
| = | 255 | × | 1 |
| X | = | 255 |