| 7 | ( | 4 | − | X | ) | = | 9 | ( | X | − | 4 | ) |
| Left side of the equation = | 7 | × | 4 | − | 7 | X |
| = | 28 | − | 7 | X |
| 28 | − | 7 | X | = | 9 | ( | X | − | 4 | ) |
| Right side of the equation = | 9 | X | − | 9 | × | 4 |
| = | 9 | X | − | 36 |
| 28 | − | 7 | X | = | 9 | X | − | 36 |
| - | 7 | X | − | 9 | X | = | - | 36 | − | 28 |
| - | 16 | X | = | - | 36 | − | 28 |
| - | 16 | X | = | - | 64 |
| 64 | = | 16 | X |
| 16 | X | = | 64 |
| X | = | 64 | ÷ | 16 |
| = | 64 | × | 1 16 |
| = | 4 | × | 1 |
| X | = | 4 |