| 250 | − | x | − | 60 | = | ( | x | − | 60 | ) | ÷ | 2 |
| 方程左边 = | 190 | − | x |
| 190 | − | x | = | ( | x | − | 60 | ) | ÷ | 2 |
| 方程右边 = | x | × | 1 2 | − | 60 | × | 1 2 |
| = | x | × | 1 2 | − | 30 |
| 190 | − | x | = | 1 2 | x | − | 30 |
| - | x | − | 1 2 | x | = | - | 30 | − | 190 |
| - | 3 2 | x | = | - | 30 | − | 190 |
| - | 3 2 | x | = | - | 220 |
| 220 | = | 3 2 | x |
3 2 | x | = | 220 |
| x | = | 220 | ÷ | 3 2 |
| = | 220 | × | 2 3 |
| x | = | 440 3 |
| x | = | 146.666667 |