| 400 | ÷ | ( | 643 10 | − | x | ) | = | 150 | ÷ | ( | 1653 10 | − | x | ) |
| 方程两边同时乘以: | ( | 643 10 | − | x | ) | , | ( | 1653 10 | − | x | ) |
| 400 | ( | 1653 10 | − | x | ) | = | 150 | ( | 643 10 | − | x | ) |
| 400 | × | 1653 10 | − | 400 | x | = | 150 | ( | 643 10 | − | x | ) |
| 400 | × | 1653 10 | − | 400 | x | = | 150 | × | 643 10 | − | 150 | x |
| 66120 | − | 400 | x | = | 9645 | − | 150 | x |
| - | 400 | x | + | 150 | x | = | 9645 | − | 66120 |
| - | 250 | x | = | 9645 | − | 66120 |
| - | 250 | x | = | - | 56475 |
| 56475 | = | 250 | x |
| 250 | x | = | 56475 |
| x | = | 56475 | ÷ | 250 |
| = | 56475 | × | 1 250 |
| = | 2259 | × | 1 10 |
| x | = | 2259 10 |
| x | = | 225.9 |