| 6400 | ÷ | x | = | 8000 | ÷ | ( | x | + | 400 | ) |
| 方程两边同时乘以: | x | , | ( | x | + | 400 | ) |
| 6400 | ( | x | + | 400 | ) | = | 8000 | x |
| 6400 | x | + | 6400 | × | 400 | = | 8000 | x |
| 6400 | x | + | 2560000 | = | 8000 | x |
| 6400 | x | − | 8000 | x | = | - | 2560000 |
| - | 1600 | x | = | - | 2560000 |
| 2560000 | = | 1600 | x |
| 1600 | x | = | 2560000 |
| x | = | 2560000 | ÷ | 1600 |
| = | 2560000 | × | 1 1600 |
| = | 1600 | × | 1 |
| x | = | 1600 |