| 500 | + | 100 | x | + | 250 | + | ( | 150 | x | − | 3500 | ) | = | 3500 |
| 方程左边 = | 750 | + | 100 | x | + | ( | 150 | x | − | 3500 | ) |
| 750 | + | 100 | x | + | ( | 150 | x | − | 3500 | ) | = | 3500 |
| 方程左边 = | 750 | + | 100 | x | + | 150 | x | − | 3500 |
| = | - | 2750 | + | 250 | x |
| - | 2750 | + | 250 | x | = | 3500 |
| 250 | x | = | 3500 | + | 2750 |
| 250 | x | = | 6250 |
| x | = | 6250 | ÷ | 250 |
| = | 6250 | × | 1 250 |
| = | 25 | × | 1 |
| x | = | 25 |