| ( | 1 2 | − | x | ) | ( | 500 | + | x | ÷ | 1 10 | × | 200 | ) | = | 270 |
| 方程左边 = | 1 2 | ( | 500 | + | x | ÷ | 1 10 | × | 200 | ) | − | x | ( | 500 | + | x | ÷ | 1 10 | × | 200 | ) |
| = | 1 2 | × | 500 | + | 1 2 | x | ÷ | 1 10 | × | 200 | − | x | ( | 500 | + | x | ÷ | 1 10 | × | 200 | ) |
| = | 250 | + | 1000 | x | − | x | ( | 500 | + | x | ÷ | 1 10 | × | 200 | ) |
| = | 250 | + | 1000 | x | − | x | × | 500 | − | x | x | ÷ | 1 10 | × | 200 |
| = | 250 | + | 1000 | x | − | x | × | 500 | − | x | x | × | 2000 |
| = | 250 | + | 500 | x | − | x | x | × | 2000 |
| 250 | + | 500 | x | − | x | x | × | 2000 | = | 270 |
| x1= | 1 20 |
| x2= | 1 5 |