| 4700 | x | + | 7900 | ( | 6 | − | x | ) | = | 42000 |
| 方程左边 = | 4700 | x | + | 7900 | × | 6 | − | 7900 | x |
| = | 4700 | x | + | 47400 | − | 7900 | x |
| = | - | 3200 | x | + | 47400 |
| - | 3200 | x | + | 47400 | = | 42000 |
| - | 3200 | x | = | 42000 | − | 47400 |
| - | 3200 | x | = | - | 5400 |
| 5400 | = | 3200 | x |
| 3200 | x | = | 5400 |
| x | = | 5400 | ÷ | 3200 |
| = | 5400 | × | 1 3200 |
| = | 27 | × | 1 16 |
| x | = | 27 16 |
| x | = | 1.6875 |