| ( | X | − | 85 | ) | ÷ | 85 | − | ( | X | − | 100 | ) | ÷ | 100 | = | 6 25 |
| Left side of the equation = | X | × | 1 85 | − | 85 | × | 1 85 | − | ( | X | − | 100 | ) | × | 1 100 |
| = | X | × | 1 85 | − | 1 | − | ( | X | − | 100 | ) | × | 1 100 |
| = | 1 85 | X | − | 1 | − | X | × | 1 100 | + | 100 | × | 1 100 |
| = | 1 85 | X | − | 1 | − | X | × | 1 100 | + | 1 |
| = | 3 1700 | X | − | 0 |
3 1700 | X | − | 0 | = | 6 25 |
| X | = | 6 25 | ÷ | 3 1700 |
| = | 6 25 | × | 1700 3 |
| = | 2 | × | 68 |
| X | = | 136 |