| ( | 200 | − | x | ) | ÷ | ( | 220 | − | x | ) | = | 29 50 |
| 方程两边同时乘以: | ( | 220 | − | x | ) |
| ( | 200 | − | x | ) | = | 29 50 | ( | 220 | − | x | ) |
| 200 | − | x | = | 29 50 | ( | 220 | − | x | ) |
| 200 | − | x | = | 29 50 | × | 220 | − | 29 50 | x |
| 200 | − | x | = | 638 5 | − | 29 50 | x |
| - | x | + | 29 50 | x | = | 638 5 | − | 200 |
| - | 21 50 | x | = | 638 5 | − | 200 |
| - | 21 50 | x | = | - | 362 5 |
362 5 | = | 21 50 | x |
21 50 | x | = | 362 5 |
| x | = | 362 5 | ÷ | 21 50 |
| = | 362 5 | × | 50 21 |
| = | 362 | × | 10 21 |
| x | = | 3620 21 |
| x | = | 172.380952 |