21 100 | − | 1 10 | ( | 30 | x | − | ( | 1 10 | + | x | ) | ) | = | 1 2 | x | − | 1 10 | ( | 6 | x | − | ( | 1 10 | − | 7 | x | ) | ) |
| 方程左边 = | 21 100 | − | 1 10 | × | 30 | x | + | 1 10 | ( | 1 10 | + | x | ) |
| = | 21 100 | − | 3 | x | + | 1 10 | ( | 1 10 | + | x | ) |
| = | 21 100 | − | 3 | x | + | 1 10 | × | 1 10 | + | 1 10 | x |
| = | 21 100 | − | 3 | x | + | 1 100 | + | 1 10 | x |
| = | 11 50 | − | 29 10 | x |
11 50 | − | 29 10 | x | = | 1 2 | x | − | 1 10 | ( | 6 | x | − | ( | 1 10 | − | 7 | x | ) | ) |
| 方程右边 = | 1 2 | x | − | 1 10 | × | 6 | x | + | 1 10 | ( | 1 10 | − | 7 | x | ) |
| = | 1 2 | x | − | 3 5 | x | + | 1 10 | ( | 1 10 | − | 7 | x | ) |
| = | - | 1 10 | x | + | 1 10 | ( | 1 10 | − | 7 | x | ) |
| = | - | 1 10 | x | + | 1 10 | × | 1 10 | − | 1 10 | × | 7 | x |
| = | - | 1 10 | x | + | 1 100 | − | 7 10 | x |
| = | - | 4 5 | x | + | 1 100 |
11 50 | − | 29 10 | x | = | - | 4 5 | x | + | 1 100 |
| - | 29 10 | x | + | 4 5 | x | = | 1 100 | − | 11 50 |
| - | 21 10 | x | = | 1 100 | − | 11 50 |
| - | 21 10 | x | = | - | 21 100 |
21 100 | = | 21 10 | x |
21 10 | x | = | 21 100 |
| x | = | 21 100 | ÷ | 21 10 |
| = | 21 100 | × | 10 21 |
| = | 1 10 | × | 1 |
| x | = | 1 10 |
| x | = | 0.1 |