| 500 | x | + | 600 | ( | 400 | − | x | ) | = | 222000 |
| Left side of the equation = | 500 | x | + | 600 | × | 400 | − | 600 | x |
| = | 500 | x | + | 240000 | − | 600 | x |
| = | - | 100 | x | + | 240000 |
| - | 100 | x | + | 240000 | = | 222000 |
| - | 100 | x | = | 222000 | − | 240000 |
| - | 100 | x | = | - | 18000 |
| 18000 | = | 100 | x |
| 100 | x | = | 18000 |
| x | = | 18000 | ÷ | 100 |
| = | 18000 | × | 1 100 |
| = | 180 | × | 1 |
| x | = | 180 |