| 30 | ÷ | x | = | 30 | ÷ | ( | x | ÷ | 25 4 | ) | − | 7 | ÷ | 10 |
| 方程两边同时乘以: | x | , | ( | 1 | ÷ | 25 4 | ) |
| 30 | ( | 1 | ÷ | 25 4 | ) | = | 30 | × | 1 | − | 7 | ÷ | 10 | × | x | ( | 1 | ÷ | 25 4 | ) |
| 30 | × | 1 | ÷ | 25 4 | = | 30 | × | 1 | − | 7 | ÷ | 10 | × | x | ( | 1 | ÷ | 25 4 | ) |
| 30 | × | 1 | ÷ | 25 4 | = | 30 | × | 1 | − | 7 | ÷ | 10 | × | x | × | 1 | ÷ | 25 4 |
24 5 | = | 30 | − | 14 125 | x |
14 125 | x | = | 30 | − | 24 5 |
14 125 | x | = | 126 5 |
| x | = | 126 5 | ÷ | 14 125 |
| = | 126 5 | × | 125 14 |
| = | 9 | × | 25 |
| x | = | 225 |