89 10 | x | + | 69 5 | ( | 510 | − | x | ) | = | 131421 10 |
| Left side of the equation = | 89 10 | x | + | 69 5 | × | 510 | − | 69 5 | x |
| = | 89 10 | x | + | 7038 | − | 69 5 | x |
| = | - | 49 10 | x | + | 7038 |
| - | 49 10 | x | + | 7038 | = | 131421 10 |
| - | 49 10 | x | = | 131421 10 | − | 7038 |
| - | 49 10 | x | = | 61041 10 |
| - | 61041 10 | = | 49 10 | x |
49 10 | x | = | - | 61041 10 |
| x | = | - | 61041 10 | ÷ | 49 10 |
| = | - | 61041 10 | × | 10 49 |
| = | - | 61041 | × | 1 49 |
| x | = | - | 61041 49 |
| x | = | - 1245.734694 |