| 1 | ÷ | x | − | 1 | ÷ | x | − | 500 | = | 1 | ÷ | 120 |
| 方程两边同时乘以: | x |
| 1 | − | 1 | ÷ | 1 | × | 1 | − | 500 | x | = | 1 | ÷ | 120 | × | x |
| - | 500 | x | − | 1 | ÷ | 120 | × | x | = | - | 1 | + | 1 | ÷ | 1 | × | 1 |
| - | 500 | x | − | 1 120 | x | = | - | 1 | + | 1 | ÷ | 1 | × | 1 |
| - | 500 | x | − | 1 120 | x | = | - | 1 | + | 1 |
| - | 60001 120 | x | = | - | 1 | + | 1 |
| - | 60001 120 | x | = | - | 0 |
| 0 | = | 60001 120 | x |
60001 120 | x | = | 0 |
| x | = | 0 | ÷ | 60001 120 |
| = | 0 | × | 120 60001 |
| x | = | 0 |
| x | = | 0 |