| ( | 12 | − | x | ) | ÷ | 4 | = | ( | 12 | − | 2 | x | ) | ÷ | 3 |
| 方程左边 = | 12 | × | 1 4 | − | x | × | 1 4 |
| = | 3 | − | x | × | 1 4 |
| 3 | − | 1 4 | x | = | ( | 12 | − | 2 | x | ) | ÷ | 3 |
| 方程右边 = | 12 | × | 1 3 | − | 2 | x | × | 1 3 |
| = | 4 | − | 2 3 | x |
| 3 | − | 1 4 | x | = | 4 | − | 2 3 | x |
| - | 1 4 | x | + | 2 3 | x | = | 4 | − | 3 |
5 12 | x | = | 4 | − | 3 |
5 12 | x | = | 1 |
| x | = | 1 | ÷ | 5 12 |
| = | 1 | × | 12 5 |
| x | = | 12 5 |
| x | = | 2.4 |