20 100 | ( | x | + | 200 | − | 250 | ) | = | x | − | 250 |
| 方程左边 = | 20 100 | x | + | 20 100 | × | 200 | − | 20 100 | × | 250 |
| = | 20 100 | x | + | 40 | − | 50 |
| = | 20 100 | x | − | 10 |
20 100 | x | − | 10 | = | x | − | 250 |
20 100 | x | − | x | = | - | 250 | + | 10 |
| - | 4 5 | x | = | - | 250 | + | 10 |
| - | 4 5 | x | = | - | 240 |
| 240 | = | 4 5 | x |
4 5 | x | = | 240 |
| x | = | 240 | ÷ | 4 5 |
| = | 240 | × | 5 4 |
| = | 60 | × | 5 |
| x | = | 300 |