| 6 | x | + | 10 | ( | 50 | − | x | ) | = | 500 | − | 78 |
| Left side of the equation = | 6 | x | + | 10 | × | 50 | − | 10 | x |
| = | 6 | x | + | 500 | − | 10 | x |
| = | - | 4 | x | + | 500 |
| - | 4 | x | + | 500 | = | 500 | − | 78 |
| Right side of the equation = | 422 |
| - | 4 | x | + | 500 | = | 422 |
| - | 4 | x | = | 422 | − | 500 |
| - | 4 | x | = | - | 78 |
| 78 | = | 4 | x |
| 4 | x | = | 78 |
| x | = | 78 | ÷ | 4 |
| = | 78 | × | 1 4 |
| = | 39 | × | 1 2 |
| x | = | 39 2 |
| x | = | 19.5 |