| 600 | + | 100 | x | = | 300 | ( | x | − | 6 | ) |
| Right side of the equation = | 300 | x | − | 300 | × | 6 |
| = | 300 | x | − | 1800 |
| 600 | + | 100 | x | = | 300 | x | − | 1800 |
| 100 | x | − | 300 | x | = | - | 1800 | − | 600 |
| - | 200 | x | = | - | 1800 | − | 600 |
| - | 200 | x | = | - | 2400 |
| 2400 | = | 200 | x |
| 200 | x | = | 2400 |
| x | = | 2400 | ÷ | 200 |
| = | 2400 | × | 1 200 |
| = | 12 | × | 1 |
| x | = | 12 |