77 10 | + | ( | 15 | X | × | 2 5 | ) | = | 81 10 | X |
| Left side of the equation = | 77 10 | + | 15 | X | × | 2 5 |
| = | 77 10 | + | 6 | X |
77 10 | + | 6 | X | = | 81 10 | X |
| 6 | X | − | 81 10 | X | = | - | 77 10 |
| - | 21 10 | X | = | - | 77 10 |
77 10 | = | 21 10 | X |
21 10 | X | = | 77 10 |
| X | = | 77 10 | ÷ | 21 10 |
| = | 77 10 | × | 10 21 |
| = | 11 | × | 1 3 |
| X | = | 11 3 |
| X | = | 3.666667 |