| ( | 25 | + | x | ) | ÷ | ( | 500 | + | x | ) | = | 3 10 |
| 方程两边同时乘以: | ( | 500 | + | x | ) |
| ( | 25 | + | x | ) | = | 3 10 | ( | 500 | + | x | ) |
| 25 | + | x | = | 3 10 | ( | 500 | + | x | ) |
| 25 | + | x | = | 3 10 | × | 500 | + | 3 10 | x |
| 25 | + | x | = | 150 | + | 3 10 | x |
| x | − | 3 10 | x | = | 150 | − | 25 |
7 10 | x | = | 150 | − | 25 |
7 10 | x | = | 125 |
| x | = | 125 | ÷ | 7 10 |
| = | 125 | × | 10 7 |
| x | = | 1250 7 |
| x | = | 178.571429 |