| 1 | X | − | 4 | ( | 2 | X | − | 3 10 | ) | = | 51 10 |
| Left side of the equation = | 1 | X | − | 4 | × | 2 | X | + | 4 | × | 3 10 |
| = | 1 | X | − | 8 | X | + | 6 5 |
| = | - | 7 | X | + | 6 5 |
| - | 7 | X | + | 6 5 | = | 51 10 |
| - | 7 | X | = | 51 10 | − | 6 5 |
| - | 7 | X | = | 39 10 |
| - | 39 10 | = | 7 | X |
| 7 | X | = | - | 39 10 |
| X | = | - | 39 10 | ÷ | 7 |
| = | - | 39 10 | × | 1 7 |
| X | = | - | 39 70 |
| X | = | - 0.557143 |