| 5 | × | 3 | X | − | 3 | ( | X | + | 3 | ) | = | 7 | X | + | 1 |
| Left side of the equation = | 15 | X | − | 3 | ( | X | + | 3 | ) |
| 15 | X | − | 3 | ( | X | + | 3 | ) | = | 7 | X | + | 1 |
| Left side of the equation = | 15 | X | − | 3 | X | − | 3 | × | 3 |
| = | 15 | X | − | 3 | X | − | 9 |
| = | 12 | X | − | 9 |
| 12 | X | − | 9 | = | 7 | X | + | 1 |
| 12 | X | − | 7 | X | = | 1 | + | 9 |
| 5 | X | = | 1 | + | 9 |
| 5 | X | = | 10 |
| X | = | 10 | ÷ | 5 |
| = | 10 | × | 1 5 |
| = | 2 | × | 1 |
| X | = | 2 |