| 40 | − | x | − | x | = | 3 | x | − | 1 | ÷ | 3 | × | ( | 40 | − | x | ) |
| 方程左边 = | 40 | − | 2 | x |
| 40 | − | 2 | x | = | 3 | x | − | 1 | ÷ | 3 | × | ( | 40 | − | x | ) |
| 方程右边 = | 3 | x | − | 1 3 | ( | 40 | − | x | ) |
| 40 | − | 2 | x | = | 3 | x | − | 1 3 | ( | 40 | − | x | ) |
| 方程右边 = | 3 | x | − | 1 3 | × | 40 | + | 1 3 | x |
| = | 3 | x | − | 40 3 | + | 1 3 | x |
| = | 10 3 | x | − | 40 3 |
| 40 | − | 2 | x | = | 10 3 | x | − | 40 3 |
| - | 2 | x | − | 10 3 | x | = | - | 40 3 | − | 40 |
| - | 16 3 | x | = | - | 40 3 | − | 40 |
| - | 16 3 | x | = | - | 160 3 |
160 3 | = | 16 3 | x |
16 3 | x | = | 160 3 |
| x | = | 160 3 | ÷ | 16 3 |
| = | 160 3 | × | 3 16 |
| = | 10 | × | 1 |
| x | = | 10 |