| 10 | × | 8 | X | − | 5 | ( | X | + | 5 | ) | = | 70 |
| Left side of the equation = | 80 | X | − | 5 | ( | X | + | 5 | ) |
| 80 | X | − | 5 | ( | X | + | 5 | ) | = | 70 |
| Left side of the equation = | 80 | X | − | 5 | X | − | 5 | × | 5 |
| = | 80 | X | − | 5 | X | − | 25 |
| = | 75 | X | − | 25 |
| 75 | X | − | 25 | = | 70 |
| 75 | X | = | 70 | + | 25 |
| 75 | X | = | 95 |
| X | = | 95 | ÷ | 75 |
| = | 95 | × | 1 75 |
| = | 19 | × | 1 15 |
| X | = | 19 15 |
| X | = | 1.266667 |