| ( | 7 | + | x | ) | × | 9 10 | = | 13 | + | x |
| Left side of the equation = | 7 | × | 9 10 | + | x | × | 9 10 |
| = | 63 10 | + | x | × | 9 10 |
63 10 | + | 9 10 | x | = | 13 | + | x |
9 10 | x | − | x | = | 13 | − | 63 10 |
| - | 1 10 | x | = | 13 | − | 63 10 |
| - | 1 10 | x | = | 67 10 |
| - | 67 10 | = | 1 10 | x |
1 10 | x | = | - | 67 10 |
| x | = | - | 67 10 | ÷ | 1 10 |
| = | - | 67 10 | × | 10 |
| = | - | 67 | × | 1 |
| x | = | - | 67 |