| ( | ( | x | + | 10 | ) | ÷ | 5 | ) | − | ( | x | − | 18 | ) | = | 0 |
| 方程左边 = | ( | x | + | 10 | ) | ÷ | 5 | − | ( | x | − | 18 | ) |
| = | x | × | 1 5 | + | 10 | × | 1 5 | − | ( | x | − | 18 | ) |
| = | x | × | 1 5 | + | 2 | − | ( | x | − | 18 | ) |
| = | 1 5 | x | + | 2 | − | x | + | 18 |
| = | - | 4 5 | x | + | 20 |
| - | 4 5 | x | + | 20 | = | 0 |
| - | 4 5 | x | = | 0 | − | 20 |
| - | 4 5 | x | = | - | 20 |
| 20 | = | 4 5 | x |
4 5 | x | = | 20 |
| x | = | 20 | ÷ | 4 5 |
| = | 20 | × | 5 4 |
| = | 5 | × | 5 |
| x | = | 25 |