| ( | 3 | x | − | 120 | ) | ÷ | ( | 2 | x | − | 120 | ) | = | 9 | ÷ | 5 |
| 方程两边同时乘以: | ( | 2 | x | − | 120 | ) |
| ( | 3 | x | − | 120 | ) | = | 9 | ÷ | 5 | × | ( | 2 | x | − | 120 | ) |
| 3 | x | − | 120 | = | 9 | ÷ | 5 | × | ( | 2 | x | − | 120 | ) |
| 3 | x | − | 120 | = | 9 | ÷ | 5 | × | 2 | x | − | 9 | ÷ | 5 | × | 120 |
| 3 | x | − | 120 | = | 18 5 | x | − | 216 |
| 3 | x | − | 18 5 | x | = | - | 216 | + | 120 |
| - | 3 5 | x | = | - | 216 | + | 120 |
| - | 3 5 | x | = | - | 96 |
| 96 | = | 3 5 | x |
3 5 | x | = | 96 |
| x | = | 96 | ÷ | 3 5 |
| = | 96 | × | 5 3 |
| = | 32 | × | 5 |
| x | = | 160 |