| 850 | ( | 500 | − | x | ) | = | ( | 850 | + | 10 | ) | ( | 500 | − | x | ) |
| 方程左边 = | 850 | × | 500 | − | 850 | x |
| = | 425000 | − | 850 | x |
| 425000 | − | 850 | x | = | ( | 850 | + | 10 | ) | ( | 500 | − | x | ) |
| 方程右边 = | 850 | ( | 500 | − | x | ) | + | 10 | ( | 500 | − | x | ) |
| = | 850 | × | 500 | − | 850 | x | + | 10 | ( | 500 | − | x | ) |
| = | 425000 | − | 850 | x | + | 10 | ( | 500 | − | x | ) |
| = | 425000 | − | 850 | x | + | 10 | × | 500 | − | 10 | x |
| = | 425000 | − | 850 | x | + | 5000 | − | 10 | x |
| = | 430000 | − | 860 | x |
| 425000 | − | 850 | x | = | 430000 | − | 860 | x |
| - | 850 | x | + | 860 | x | = | 430000 | − | 425000 |
| 10 | x | = | 430000 | − | 425000 |
| 10 | x | = | 5000 |
| x | = | 5000 | ÷ | 10 |
| = | 5000 | × | 1 10 |
| = | 500 | × | 1 |
| x | = | 500 |