| ( | x | − | 6 | ) | ÷ | 3 10 | = | ( | x | − | 9 | ) | ÷ | 9 40 |
| 方程左边 = | x | × | 10 3 | − | 6 | × | 10 3 |
| = | x | × | 10 3 | − | 20 |
10 3 | x | − | 20 | = | ( | x | − | 9 | ) | ÷ | 9 40 |
| 方程右边 = | x | × | 40 9 | − | 9 | × | 40 9 |
| = | x | × | 40 9 | − | 40 |
10 3 | x | − | 20 | = | 40 9 | x | − | 40 |
10 3 | x | − | 40 9 | x | = | - | 40 | + | 20 |
| - | 10 9 | x | = | - | 40 | + | 20 |
| - | 10 9 | x | = | - | 20 |
| 20 | = | 10 9 | x |
10 9 | x | = | 20 |
| x | = | 20 | ÷ | 10 9 |
| = | 20 | × | 9 10 |
| = | 2 | × | 9 |
| x | = | 18 |