| 5 | ( | 2 | + | 2 | ( | - | 15 | − | x | ) | ) | + | 13 | = | 3 |
| 方程左边 = | 5 | × | 2 | + | 5 | × | 2 | ( | - | 15 | − | x | ) | + | 13 |
| = | 10 | + | 10 | ( | - | 15 | − | x | ) | + | 13 |
| = | 23 | + | 10 | ( | - | 15 | − | x | ) |
| = | 23 | − | 10 | × | 15 | − | 10 | x |
| = | 23 | − | 150 | − | 10 | x |
| = | - | 127 | − | 10 | x |
| - | 127 | − | 10 | x | = | 3 |
| - | 10 | x | = | 3 | + | 127 |
| - | 10 | x | = | 130 |
| - | 130 | = | 10 | x |
| 10 | x | = | - | 130 |
| x | = | - | 130 | ÷ | 10 |
| = | - | 130 | × | 1 10 |
| = | - | 13 | × | 1 |
| x | = | - | 13 |