| x | − | 1 2 | x | + | 45 | = | ( | 1 2 | x | + | 45 | ) | × | 3 4 |
| 方程左边 = | 1 2 | x | + | 45 |
1 2 | x | + | 45 | = | ( | 1 2 | x | + | 45 | ) | × | 3 4 |
| 方程右边 = | 1 2 | x | × | 3 4 | + | 45 | × | 3 4 |
| = | 3 8 | x | + | 135 4 |
1 2 | x | + | 45 | = | 3 8 | x | + | 135 4 |
1 2 | x | − | 3 8 | x | = | 135 4 | − | 45 |
1 8 | x | = | 135 4 | − | 45 |
1 8 | x | = | - | 45 4 |
| x | = | - | 45 4 | ÷ | 1 8 |
| = | - | 45 4 | × | 8 |
| = | - | 45 | × | 2 |
| x | = | - | 90 |