| 6000 | + | ( | 30 | − | x | ) | ( | 200 | + | 10 | x | ) | = | 12250 |
| 方程左边 = | 6000 | + | 30 | ( | 200 | + | 10 | x | ) | − | x | ( | 200 | + | 10 | x | ) |
| = | 6000 | + | 30 | × | 200 | + | 30 | × | 10 | x | − | x | ( | 200 | + | 10 | x | ) |
| = | 6000 | + | 6000 | + | 300 | x | − | x | ( | 200 | + | 10 | x | ) |
| = | 12000 | + | 300 | x | − | x | ( | 200 | + | 10 | x | ) |
| = | 12000 | + | 300 | x | − | x | × | 200 | − | x | × | 10 | x |
| = | 12000 | + | 100 | x | − | x | × | 10 | x |
| 12000 | + | 100 | x | − | x | × | 10 | x | = | 12250 |