| 2 | ÷ | 21 | × | x | − | 2 | ÷ | 21 | = | 1 | ÷ | 7 | × | x | − | 18 | ÷ | 35 | − | 1 | ÷ | 7 |
| 方程左边 = | 2 21 | x | − | 2 21 |
2 21 | x | − | 2 21 | = | 1 | ÷ | 7 | × | x | − | 18 | ÷ | 35 | − | 1 | ÷ | 7 |
| 方程右边 = | 1 7 | x | − | 18 35 | − | 1 7 |
| = | 1 7 | x | − | 23 35 |
2 21 | x | − | 2 21 | = | 1 7 | x | − | 23 35 |
2 21 | x | − | 1 7 | x | = | - | 23 35 | + | 2 21 |
| - | 1 21 | x | = | - | 23 35 | + | 2 21 |
| - | 1 21 | x | = | - | 59 105 |
59 105 | = | 1 21 | x |
1 21 | x | = | 59 105 |
| x | = | 59 105 | ÷ | 1 21 |
| = | 59 105 | × | 21 |
| = | 59 5 | × | 1 |
| x | = | 59 5 |
| x | = | 11.8 |