| ( | 4 | ÷ | 15 | ) | ÷ | ( | 4 | ÷ | 25 | ) | = | ( | 4 | ÷ | 3 | ) | ÷ | ( | x | ÷ | 5 | ) |
| 方程两边同时乘以: | ( | 4 | ÷ | 25 | ) | , | ( | x | ÷ | 5 | ) |
| ( | 4 | ÷ | 15 | ) | ( | x | ÷ | 5 | ) | = | ( | 4 | ÷ | 3 | ) | ( | 4 | ÷ | 25 | ) |
| 4 | ÷ | 15 | × | ( | x | ÷ | 5 | ) | = | ( | 4 | ÷ | 3 | ) | ( | 4 | ÷ | 25 | ) |
| 4 | ÷ | 15 | × | ( | x | ÷ | 5 | ) | = | 4 | ÷ | 3 | × | ( | 4 | ÷ | 25 | ) |
4 15 | ( | x | ÷ | 5 | ) | = | 4 3 | ( | 4 | ÷ | 25 | ) |
4 15 | x | ÷ | 5 | = | 4 3 | ( | 4 | ÷ | 25 | ) |
4 15 | x | ÷ | 5 | = | 4 3 | × | 4 | ÷ | 25 |
4 75 | x | = | 16 75 |
| x | = | 16 75 | ÷ | 4 75 |
| = | 16 75 | × | 75 4 |
| = | 4 | × | 1 |
| x | = | 4 |