| 6 | ( | x | − | 850 | ) | = | 7 | ( | x | − | 1200 | ) |
| Left side of the equation = | 6 | x | − | 6 | × | 850 |
| = | 6 | x | − | 5100 |
| 6 | x | − | 5100 | = | 7 | ( | x | − | 1200 | ) |
| Right side of the equation = | 7 | x | − | 7 | × | 1200 |
| = | 7 | x | − | 8400 |
| 6 | x | − | 5100 | = | 7 | x | − | 8400 |
| 6 | x | − | 7 | x | = | - | 8400 | + | 5100 |
| - | x | = | - | 8400 | + | 5100 |
| - | x | = | - | 8400 | + | 5100 |
| - | x | = | - | 3300 |
| 3300 | = | x |
| x | = | 3300 |