| ( | X | + | 6 | ) | × | 20 | = | ( | X | + | 6 | + | X | ) | × | 12 |
| Left side of the equation = | X | × | 20 | + | 6 | × | 20 |
| = | X | × | 20 | + | 120 |
| 20 | X | + | 120 | = | ( | X | + | 6 | + | X | ) | × | 12 |
| Right side of the equation = | X | × | 12 | + | 6 | × | 12 | + | X | × | 12 |
| = | X | × | 12 | + | 72 | + | X | × | 12 |
| = | 24 | X | + | 72 |
| 20 | X | + | 120 | = | 24 | X | + | 72 |
| 20 | X | − | 24 | X | = | 72 | − | 120 |
| - | 4 | X | = | 72 | − | 120 |
| - | 4 | X | = | - | 48 |
| 48 | = | 4 | X |
| 4 | X | = | 48 |
| X | = | 48 | ÷ | 4 |
| = | 48 | × | 1 4 |
| = | 12 | × | 1 |
| X | = | 12 |