| 6 | x | + | 10 | ( | 50 | − | x | ) | + | 3 | = | 500 | − | 78 |
| Left side of the equation = | 6 | x | + | 10 | × | 50 | − | 10 | x | + | 3 |
| = | 6 | x | + | 500 | − | 10 | x | + | 3 |
| = | - | 4 | x | + | 503 |
| - | 4 | x | + | 503 | = | 500 | − | 78 |
| Right side of the equation = | 422 |
| - | 4 | x | + | 503 | = | 422 |
| - | 4 | x | = | 422 | − | 503 |
| - | 4 | x | = | - | 81 |
| 81 | = | 4 | x |
| 4 | x | = | 81 |
| x | = | 81 | ÷ | 4 |
| = | 81 | × | 1 4 |
| x | = | 81 4 |
| x | = | 20.25 |