| 200 | x | + | ( | 100 | − | x | ) | × | 450 | = | 35000 |
| 方程左边 = | 200 | x | + | 100 | × | 450 | − | x | × | 450 |
| = | 200 | x | + | 45000 | − | x | × | 450 |
| = | - | 250 | x | + | 45000 |
| - | 250 | x | + | 45000 | = | 35000 |
| - | 250 | x | = | 35000 | − | 45000 |
| - | 250 | x | = | - | 10000 |
| 10000 | = | 250 | x |
| 250 | x | = | 10000 |
| x | = | 10000 | ÷ | 250 |
| = | 10000 | × | 1 250 |
| = | 40 | × | 1 |
| x | = | 40 |