| 3 | ÷ | 5 | × | x | + | 20 | = | 7 | ÷ | 5 | × | ( | x | − | 20 | ) |
| 方程左边 = | 3 5 | x | + | 20 |
3 5 | x | + | 20 | = | 7 | ÷ | 5 | × | ( | x | − | 20 | ) |
| 方程右边 = | 7 5 | ( | x | − | 20 | ) |
3 5 | x | + | 20 | = | 7 5 | ( | x | − | 20 | ) |
| 方程右边 = | 7 5 | x | − | 7 5 | × | 20 |
| = | 7 5 | x | − | 28 |
3 5 | x | + | 20 | = | 7 5 | x | − | 28 |
3 5 | x | − | 7 5 | x | = | - | 28 | − | 20 |
| - | 4 5 | x | = | - | 28 | − | 20 |
| - | 4 5 | x | = | - | 48 |
| 48 | = | 4 5 | x |
4 5 | x | = | 48 |
| x | = | 48 | ÷ | 4 5 |
| = | 48 | × | 5 4 |
| = | 12 | × | 5 |
| x | = | 60 |