| 7 | ÷ | 12 | + | ( | 1 | ÷ | 12 | − | 1 | ÷ | 20 | ) | x | = | 1 |
| 方程左边 = | 7 12 | + | ( | 1 | ÷ | 12 | − | 1 | ÷ | 20 | ) | x |
7 12 | + | ( | 1 | ÷ | 12 | − | 1 | ÷ | 20 | ) | x | = | 1 |
| 方程左边 = | 7 12 | + | 1 | ÷ | 12 | × | x | − | 1 | ÷ | 20 | × | x |
| = | 7 12 | + | 1 12 | x | − | 1 20 | x |
| = | 7 12 | + | 1 30 | x |
7 12 | + | 1 30 | x | = | 1 |
1 30 | x | = | 1 | − | 7 12 |
1 30 | x | = | 5 12 |
| x | = | 5 12 | ÷ | 1 30 |
| = | 5 12 | × | 30 |
| = | 5 2 | × | 5 |
| x | = | 25 2 |
| x | = | 12.5 |