| ( | 1 5 | − | 1 20 | ) | x | + | ( | - | 1 5 | − | 1 20 | ) | ( | 1 | − | x | ) | = | 0 |
| 方程左边 = | 1 5 | x | − | 1 20 | x | + | ( | - | 1 5 | − | 1 20 | ) | ( | 1 | − | x | ) |
| = | 3 20 | x | + | ( | - | 1 5 | − | 1 20 | ) | ( | 1 | − | x | ) |
| = | 3 20 | x | − | 1 5 | ( | 1 | − | x | ) | − | 1 20 | ( | 1 | − | x | ) |
| = | 3 20 | x | − | 1 5 | × | 1 | + | 1 5 | x | − | 1 20 | ( | 1 | − | x | ) |
| = | 3 20 | x | − | 1 5 | + | 1 5 | x | − | 1 20 | ( | 1 | − | x | ) |
| = | 7 20 | x | − | 1 5 | − | 1 20 | ( | 1 | − | x | ) |
| = | 7 20 | x | − | 1 5 | − | 1 20 | × | 1 | + | 1 20 | x |
| = | 7 20 | x | − | 1 5 | − | 1 20 | + | 1 20 | x |
| = | 2 5 | x | − | 1 4 |
2 5 | x | − | 1 4 | = | 0 |
2 5 | x | = | 0 | + | 1 4 |
2 5 | x | = | 1 4 |
| x | = | 1 4 | ÷ | 2 5 |
| = | 1 4 | × | 5 2 |
| x | = | 5 8 |
| x | = | 0.625 |