| 400 | ÷ | ( | 165 | − | x | ) | = | 150 | ÷ | ( | 643 10 | − | x | ) |
| 方程两边同时乘以: | ( | 165 | − | x | ) | , | ( | 643 10 | − | x | ) |
| 400 | ( | 643 10 | − | x | ) | = | 150 | ( | 165 | − | x | ) |
| 400 | × | 643 10 | − | 400 | x | = | 150 | ( | 165 | − | x | ) |
| 400 | × | 643 10 | − | 400 | x | = | 150 | × | 165 | − | 150 | x |
| 25720 | − | 400 | x | = | 24750 | − | 150 | x |
| - | 400 | x | + | 150 | x | = | 24750 | − | 25720 |
| - | 250 | x | = | 24750 | − | 25720 |
| - | 250 | x | = | - | 970 |
| 970 | = | 250 | x |
| 250 | x | = | 970 |
| x | = | 970 | ÷ | 250 |
| = | 970 | × | 1 250 |
| = | 97 | × | 1 25 |
| x | = | 97 25 |
| x | = | 3.88 |