20 100 | x | + | ( | 600 | − | x | ) | × | 5 100 | = | 600 | × | 15 100 |
| 方程左边 = | 20 100 | x | + | 600 | × | 5 100 | − | x | × | 5 100 |
| = | 20 100 | x | + | 30 | − | x | × | 5 100 |
| = | 3 20 | x | + | 30 |
3 20 | x | + | 30 | = | 600 | × | 15 100 |
| 方程右边 = | 90 |
3 20 | x | + | 30 | = | 90 |
3 20 | x | = | 90 | − | 30 |
3 20 | x | = | 60 |
| x | = | 60 | ÷ | 3 20 |
| = | 60 | × | 20 3 |
| = | 20 | × | 20 |
| x | = | 400 |