| ( | 5 | x | + | 300 | ) | ( | 200 | − | x | ) | − | ( | 5 | x | + | 300 | ) | × | 100 | = | 32000 |
| 方程左边 = | 5 | x | ( | 200 | − | x | ) | + | 300 | ( | 200 | − | x | ) | − | ( | 5 | x | + | 300 | ) | × | 100 |
| = | 5 | x | × | 200 | − | 5 | x | x | + | 300 | ( | 200 | − | x | ) | − | ( | 5 | x | + | 300 | ) | × | 100 |
| = | 1000 | x | − | 5 | x | x | + | 300 | ( | 200 | − | x | ) | − | ( | 5 | x | + | 300 | ) | × | 100 |
| = | 1000 | x | − | 5 | x | x | + | 300 | × | 200 | − | 300 | x | − | ( | 5 | x | + | 300 | ) | × | 100 |
| = | 1000 | x | − | 5 | x | x | + | 60000 | − | 300 | x | − | ( | 5 | x | + | 300 | ) | × | 100 |
| = | 700 | x | − | 5 | x | x | + | 60000 | − | ( | 5 | x | + | 300 | ) | × | 100 |
| = | 700 | x | − | 5 | x | x | + | 60000 | − | 5 | x | × | 100 | − | 300 | × | 100 |
| = | 700 | x | − | 5 | x | x | + | 60000 | − | 500 | x | − | 30000 |
| = | 200 | x | − | 5 | x | x | + | 30000 |
| 200 | x | − | 5 | x | x | + | 30000 | = | 32000 |