| ( | 7 | − | x | ) | ÷ | ( | 13 | + | x | ) | = | 1 | ÷ | 3 |
| 方程两边同时乘以: | ( | 13 | + | x | ) |
| ( | 7 | − | x | ) | = | 1 | ÷ | 3 | × | ( | 13 | + | x | ) |
| 7 | − | x | = | 1 | ÷ | 3 | × | ( | 13 | + | x | ) |
| 7 | − | x | = | 1 | ÷ | 3 | × | 13 | + | 1 | ÷ | 3 | × | x |
| 7 | − | x | = | 13 3 | + | 1 3 | x |
| - | x | − | 1 3 | x | = | 13 3 | − | 7 |
| - | 4 3 | x | = | 13 3 | − | 7 |
| - | 4 3 | x | = | - | 8 3 |
8 3 | = | 4 3 | x |
4 3 | x | = | 8 3 |
| x | = | 8 3 | ÷ | 4 3 |
| = | 8 3 | × | 3 4 |
| = | 2 | × | 1 |
| x | = | 2 |