| 100 | × | 300 | + | ( | 100 | − | x | ) | ( | 300 | + | 2 | x | ) | + | 50 | ( | 400 | − | 2 | x | ) | − | 60 | × | 1000 | = | 15200 |
| 方程左边 = | 30000 | + | ( | 100 | − | x | ) | ( | 300 | + | 2 | x | ) | + | 50 | ( | 400 | − | 2 | x | ) | − | 60000 |
| = | - | 30000 | + | ( | 100 | − | x | ) | ( | 300 | + | 2 | x | ) | + | 50 | ( | 400 | − | 2 | x | ) |
| - | 30000 | + | ( | 100 | − | x | ) | ( | 300 | + | 2 | x | ) | + | 50 | ( | 400 | − | 2 | x | ) | = | 15200 |
| 方程左边 = | - | 30000 | + | 100 | ( | 300 | + | 2 | x | ) | − | x | ( | 300 | + | 2 | x | ) | + | 50 | ( | 400 | − | 2 | x | ) |
| = | - | 30000 | + | 100 | × | 300 | + | 100 | × | 2 | x | − | x | ( | 300 | + | 2 | x | ) | + | 50 | ( | 400 | − | 2 | x | ) |
| = | - | 30000 | + | 30000 | + | 200 | x | − | x | ( | 300 | + | 2 | x | ) | + | 50 | ( | 400 | − | 2 | x | ) |
| = | - | 0 | + | 200 | x | − | x | ( | 300 | + | 2 | x | ) | + | 50 | ( | 400 | − | 2 | x | ) |
| = | 200 | x | − | x | × | 300 | − | x | × | 2 | x | + | 50 | ( | 400 | − | 2 | x | ) |
| = | - | 100 | x | − | x | × | 2 | x | + | 50 | ( | 400 | − | 2 | x | ) |
| = | - | 100 | x | − | x | × | 2 | x | + | 50 | × | 400 | − | 50 | × | 2 | x |
| = | - | 100 | x | − | x | × | 2 | x | + | 20000 | − | 100 | x |
| = | - | 200 | x | − | x | × | 2 | x | + | 20000 |
| - | 200 | x | − | x | × | 2 | x | + | 20000 | = | 15200 |