| 30 | × | 100 | ÷ | X | ÷ | 21 20 | ÷ | 90 | × | 100 | = | 48 |
| Multiply both sides of the equation by: | X |
| 30 | × | 100 | ÷ | 21 20 | ÷ | 90 | × | 100 | = | 48 | X |
| - | 48 | X | = | - | 30 | × | 100 | ÷ | 21 20 | ÷ | 90 | × | 100 |
| - | 48 | X | = | - | 200000 63 |
200000 63 | = | 48 | X |
| 48 | X | = | 200000 63 |
| X | = | 200000 63 | ÷ | 48 |
| = | 200000 63 | × | 1 48 |
| = | 12500 63 | × | 1 3 |
| X | = | 12500 189 |
| X | = | 66.137566 |