| ( | 100 | − | X | ) | ÷ | ( | X | − | 91 | ) | = | 769 50 |
| Multiply both sides of the equation by: | ( | X | − | 91 | ) |
| ( | 100 | − | X | ) | = | 769 50 | ( | X | − | 91 | ) |
| 100 | − | X | = | 769 50 | ( | X | − | 91 | ) |
| 100 | − | X | = | 769 50 | X | − | 769 50 | × | 91 |
| 100 | − | X | = | 769 50 | X | − | 69979 50 |
| - | X | − | 769 50 | X | = | - | 69979 50 | − | 100 |
| - | 819 50 | X | = | - | 69979 50 | − | 100 |
| - | 819 50 | X | = | - | 74979 50 |
74979 50 | = | 819 50 | X |
819 50 | X | = | 74979 50 |
| X | = | 74979 50 | ÷ | 819 50 |
| = | 74979 50 | × | 50 819 |
| = | 8331 | × | 1 91 |
| X | = | 8331 91 |
| X | = | 91.549451 |