| 1 | + | 2 | ( | 1 | − | ( | - | 18 | + | 4 | x | ) | ) | = | - | 5 | ( | 7 | x | + | 13 | ) |
| 方程左边 = | 1 | + | 2 | × | 1 | − | 2 | ( | - | 18 | + | 4 | x | ) |
| = | 1 | + | 2 | − | 2 | ( | - | 18 | + | 4 | x | ) |
| = | 3 | − | 2 | ( | - | 18 | + | 4 | x | ) |
| = | 3 | + | 2 | × | 18 | − | 2 | × | 4 | x |
| = | 3 | + | 36 | − | 8 | x |
| = | 39 | − | 8 | x |
| 39 | − | 8 | x | = | - | 5 | ( | 7 | x | + | 13 | ) |
| 方程右边 = | - | 5 | × | 7 | x | − | 5 | × | 13 |
| = | - | 35 | x | − | 65 |
| 39 | − | 8 | x | = | - | 35 | x | − | 65 |
| - | 8 | x | + | 35 | x | = | - | 65 | − | 39 |
| 27 | x | = | - | 65 | − | 39 |
| 27 | x | = | - | 104 |
| x | = | - | 104 | ÷ | 27 |
| = | - | 104 | × | 1 27 |
| x | = | - | 104 27 |
| x | = | - 3.851852 |