| 300 | ÷ | x | − | 3 | = | 300 | ÷ | ( | 5 | ÷ | 4 | × | x | ) |
| 方程两边同时乘以: | x | , | ( | 5 | ÷ | 4 | × | 1 | ) |
| 300 | ( | 5 | ÷ | 4 | × | 1 | ) | − | 3 | x | ( | 5 | ÷ | 4 | × | 1 | ) | = | 300 | × | 1 |
| 300 | × | 5 | ÷ | 4 | × | 1 | − | 3 | x | ( | 5 | ÷ | 4 | × | 1 | ) | = | 300 | × | 1 |
| 375 | − | 3 | x | ( | 5 | ÷ | 4 | × | 1 | ) | = | 300 |
| 375 | − | 3 | x | × | 5 | ÷ | 4 | × | 1 | = | 300 |
| 375 | − | 15 4 | x | = | 300 |
| - | 15 4 | x | = | 300 | − | 375 |
| - | 15 4 | x | = | - | 75 |
| 75 | = | 15 4 | x |
15 4 | x | = | 75 |
| x | = | 75 | ÷ | 15 4 |
| = | 75 | × | 4 15 |
| = | 5 | × | 4 |
| x | = | 20 |