| 200 | x | + | 500 | ( | 9 | − | x | ) | = | 3000 |
| Left side of the equation = | 200 | x | + | 500 | × | 9 | − | 500 | x |
| = | 200 | x | + | 4500 | − | 500 | x |
| = | - | 300 | x | + | 4500 |
| - | 300 | x | + | 4500 | = | 3000 |
| - | 300 | x | = | 3000 | − | 4500 |
| - | 300 | x | = | - | 1500 |
| 1500 | = | 300 | x |
| 300 | x | = | 1500 |
| x | = | 1500 | ÷ | 300 |
| = | 1500 | × | 1 300 |
| = | 5 | × | 1 |
| x | = | 5 |