| 7 | + | x | = | 100 | ÷ | 9 | × | ( | 13 | + | x | ) |
| 方程右边 = | 100 9 | ( | 13 | + | x | ) |
| 7 | + | x | = | 100 9 | ( | 13 | + | x | ) |
| 方程右边 = | 100 9 | × | 13 | + | 100 9 | x |
| = | 1300 9 | + | 100 9 | x |
| 7 | + | x | = | 1300 9 | + | 100 9 | x |
| x | − | 100 9 | x | = | 1300 9 | − | 7 |
| - | 91 9 | x | = | 1300 9 | − | 7 |
| - | 91 9 | x | = | 1237 9 |
| - | 1237 9 | = | 91 9 | x |
91 9 | x | = | - | 1237 9 |
| x | = | - | 1237 9 | ÷ | 91 9 |
| = | - | 1237 9 | × | 9 91 |
| = | - | 1237 | × | 1 91 |
| x | = | - | 1237 91 |
| x | = | - 13.593407 |