| 12 | ÷ | X | − | 12 | ÷ | ( | 4 | + | X | ) | = | 4 |
| 方程两边同时乘以: | X |
| 12 | − | 12 | ÷ | ( | 4 | + | X | ) | × | X | = | 4 | X |
| 方程两边同时乘以: | ( | 4 | + | X | ) |
| 12 | ( | 4 | + | X | ) | − | 12 | X | = | 4 | X | ( | 4 | + | X | ) |
| 12 | × | 4 | + | 12 | X | − | 12 | X | = | 4 | X | ( | 4 | + | X | ) |
| 12 | × | 4 | + | 12 | X | − | 12 | X | = | 4 | X | × | 4 | + | 4 | X | X |
| 48 | + | 12 | X | − | 12 | X | = | 16 | X | + | 4 | X | X |
| 48 | + | 0 | X | = | 16 | X | + | 4 | X | X |