| 62 | X | − | ( | X | − | 10 | ) | × | 90 | = | 320 |
| Left side of the equation = | 62 | X | − | X | × | 90 | + | 10 | × | 90 |
| = | 62 | X | − | X | × | 90 | + | 900 |
| = | - | 28 | X | + | 900 |
| - | 28 | X | + | 900 | = | 320 |
| - | 28 | X | = | 320 | − | 900 |
| - | 28 | X | = | - | 580 |
| 580 | = | 28 | X |
| 28 | X | = | 580 |
| X | = | 580 | ÷ | 28 |
| = | 580 | × | 1 28 |
| = | 145 | × | 1 7 |
| X | = | 145 7 |
| X | = | 20.714286 |