30571 5 | = | ( | 502 | − | x | ) | × | 69 5 | + | 89 10 | x |
| 方程右边 = | 502 | × | 69 5 | − | x | × | 69 5 | + | 89 10 | x |
| = | 34638 5 | − | x | × | 69 5 | + | 89 10 | x |
| = | 34638 5 | − | 49 10 | x |
30571 5 | = | 34638 5 | − | 49 10 | x |
49 10 | x | = | 34638 5 | − | 30571 5 |
49 10 | x | = | 4067 5 |
| x | = | 4067 5 | ÷ | 49 10 |
| = | 4067 5 | × | 10 49 |
| = | 83 | × | 2 |
| x | = | 166 |