| 310 | x | + | 460 | ( | 50 | − | x | ) | = | 20000 |
| Left side of the equation = | 310 | x | + | 460 | × | 50 | − | 460 | x |
| = | 310 | x | + | 23000 | − | 460 | x |
| = | - | 150 | x | + | 23000 |
| - | 150 | x | + | 23000 | = | 20000 |
| - | 150 | x | = | 20000 | − | 23000 |
| - | 150 | x | = | - | 3000 |
| 3000 | = | 150 | x |
| 150 | x | = | 3000 |
| x | = | 3000 | ÷ | 150 |
| = | 3000 | × | 1 150 |
| = | 20 | × | 1 |
| x | = | 20 |