| ( | 230 | + | x | ) | ÷ | ( | 400 | + | x | ) | = | 33 50 |
| 方程两边同时乘以: | ( | 400 | + | x | ) |
| ( | 230 | + | x | ) | = | 33 50 | ( | 400 | + | x | ) |
| 230 | + | x | = | 33 50 | ( | 400 | + | x | ) |
| 230 | + | x | = | 33 50 | × | 400 | + | 33 50 | x |
| 230 | + | x | = | 264 | + | 33 50 | x |
| x | − | 33 50 | x | = | 264 | − | 230 |
17 50 | x | = | 264 | − | 230 |
17 50 | x | = | 34 |
| x | = | 34 | ÷ | 17 50 |
| = | 34 | × | 50 17 |
| = | 2 | × | 50 |
| x | = | 100 |