| 5 | ( | 4 | − | X | ) | = | 3 | ( | X | − | 3 | ) | − | 15 |
| Left side of the equation = | 5 | × | 4 | − | 5 | X |
| = | 20 | − | 5 | X |
| 20 | − | 5 | X | = | 3 | ( | X | − | 3 | ) | − | 15 |
| Right side of the equation = | 3 | X | − | 3 | × | 3 | − | 15 |
| = | 3 | X | − | 9 | − | 15 |
| = | 3 | X | − | 24 |
| 20 | − | 5 | X | = | 3 | X | − | 24 |
| - | 5 | X | − | 3 | X | = | - | 24 | − | 20 |
| - | 8 | X | = | - | 24 | − | 20 |
| - | 8 | X | = | - | 44 |
| 44 | = | 8 | X |
| 8 | X | = | 44 |
| X | = | 44 | ÷ | 8 |
| = | 44 | × | 1 8 |
| = | 11 | × | 1 2 |
| X | = | 11 2 |
| X | = | 5.5 |