| 139 | ÷ | ( | 139 | − | x | ) | ÷ | 9 10 | = | 13 10 |
| Multiply both sides of the equation by: | ( | 139 | − | x | ) |
| 139 | ÷ | 9 10 | = | 13 10 | ( | 139 | − | x | ) |
| 139 | ÷ | 9 10 | = | 13 10 | × | 139 | − | 13 10 | x |
1390 9 | = | 1807 10 | − | 13 10 | x |
13 10 | x | = | 1807 10 | − | 1390 9 |
13 10 | x | = | 2363 90 |
| x | = | 2363 90 | ÷ | 13 10 |
| = | 2363 90 | × | 10 13 |
| = | 2363 9 | × | 1 13 |
| x | = | 2363 117 |
| x | = | 20.196581 |