| 124 | + | 10 | × | 2 | = | 2 | ( | X | + | 18 | ) | + | 4 | X |
| Left side of the equation = | 124 | + | 20 |
| = | 144 |
| 144 | = | 2 | ( | X | + | 18 | ) | + | 4 | X |
| Right side of the equation = | 2 | X | + | 2 | × | 18 | + | 4 | X |
| = | 2 | X | + | 36 | + | 4 | X |
| = | 6 | X | + | 36 |
| 144 | = | 6 | X | + | 36 |
| - | 6 | X | = | 36 | − | 144 |
| - | 6 | X | = | - | 108 |
| 108 | = | 6 | X |
| 6 | X | = | 108 |
| X | = | 108 | ÷ | 6 |
| = | 108 | × | 1 6 |
| = | 18 | × | 1 |
| X | = | 18 |