| ( | 100 | + | x | ) | ÷ | ( | 175 | + | x | ) | = | 309 500 |
| 方程两边同时乘以: | ( | 175 | + | x | ) |
| ( | 100 | + | x | ) | = | 309 500 | ( | 175 | + | x | ) |
| 100 | + | x | = | 309 500 | ( | 175 | + | x | ) |
| 100 | + | x | = | 309 500 | × | 175 | + | 309 500 | x |
| 100 | + | x | = | 2163 20 | + | 309 500 | x |
| x | − | 309 500 | x | = | 2163 20 | − | 100 |
191 500 | x | = | 2163 20 | − | 100 |
191 500 | x | = | 163 20 |
| x | = | 163 20 | ÷ | 191 500 |
| = | 163 20 | × | 500 191 |
| = | 163 | × | 25 191 |
| x | = | 4075 191 |
| x | = | 21.335079 |