| 2 | ( | ( | 60 | − | x | ) | ÷ | 60 | ) | = | 1 | ( | ( | 120 | − | x | ) | ÷ | 120 | ) |
| 方程左边 = | 2 | ( | 60 | − | x | ) | ÷ | 60 |
| = | 1 30 | ( | 60 | − | x | ) |
| = | 1 30 | × | 60 | − | 1 30 | x |
| = | 2 | − | 1 30 | x |
| 2 | − | 1 30 | x | = | 1 | ( | ( | 120 | − | x | ) | ÷ | 120 | ) |
| 方程右边 = | 1 | ( | 120 | − | x | ) | ÷ | 120 |
| = | 1 120 | ( | 120 | − | x | ) |
| = | 1 120 | × | 120 | − | 1 120 | x |
| = | 1 | − | 1 120 | x |
| 2 | − | 1 30 | x | = | 1 | − | 1 120 | x |
| - | 1 30 | x | + | 1 120 | x | = | 1 | − | 2 |
| - | 1 40 | x | = | 1 | − | 2 |
| - | 1 40 | x | = | - | 1 |
| 1 | = | 1 40 | x |
1 40 | x | = | 1 |
| x | = | 1 | ÷ | 1 40 |
| = | 1 | × | 40 |
| x | = | 40 |