7 100 | = | ( | 7 10 | − | 1 20 | ) | X | + | 1 20 |
| Right side of the equation = | 7 10 | X | − | 1 20 | X | + | 1 20 |
| = | 13 20 | X | + | 1 20 |
7 100 | = | 13 20 | X | + | 1 20 |
| - | 13 20 | X | = | 1 20 | − | 7 100 |
| - | 13 20 | X | = | - | 1 50 |
1 50 | = | 13 20 | X |
13 20 | X | = | 1 50 |
| X | = | 1 50 | ÷ | 13 20 |
| = | 1 50 | × | 20 13 |
| = | 1 5 | × | 2 13 |
| X | = | 2 65 |
| X | = | 0.030769 |