| ( | 18 | x | − | 120 | ) | ÷ | ( | 17 | x | − | 160 | ) | = | 6 | ÷ | 5 |
| 方程两边同时乘以: | ( | 17 | x | − | 160 | ) |
| ( | 18 | x | − | 120 | ) | = | 6 | ÷ | 5 | × | ( | 17 | x | − | 160 | ) |
| 18 | x | − | 120 | = | 6 | ÷ | 5 | × | ( | 17 | x | − | 160 | ) |
| 18 | x | − | 120 | = | 6 | ÷ | 5 | × | 17 | x | − | 6 | ÷ | 5 | × | 160 |
| 18 | x | − | 120 | = | 102 5 | x | − | 192 |
| 18 | x | − | 102 5 | x | = | - | 192 | + | 120 |
| - | 12 5 | x | = | - | 192 | + | 120 |
| - | 12 5 | x | = | - | 72 |
| 72 | = | 12 5 | x |
12 5 | x | = | 72 |
| x | = | 72 | ÷ | 12 5 |
| = | 72 | × | 5 12 |
| = | 6 | × | 5 |
| x | = | 30 |