| 25 | X | × | 2 | + | 2 | ( | X | − | 4 | ) | = | 90 |
| Left side of the equation = | 50 | X | + | 2 | ( | X | − | 4 | ) |
| 50 | X | + | 2 | ( | X | − | 4 | ) | = | 90 |
| Left side of the equation = | 50 | X | + | 2 | X | − | 2 | × | 4 |
| = | 50 | X | + | 2 | X | − | 8 |
| = | 52 | X | − | 8 |
| 52 | X | − | 8 | = | 90 |
| 52 | X | = | 90 | + | 8 |
| 52 | X | = | 98 |
| X | = | 98 | ÷ | 52 |
| = | 98 | × | 1 52 |
| = | 49 | × | 1 26 |
| X | = | 49 26 |
| X | = | 1.884615 |