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