| ( | 102 | + | x | ) | ÷ | ( | 168 | + | x | ) | = | 21 125 |
| 方程两边同时乘以: | ( | 168 | + | x | ) |
| ( | 102 | + | x | ) | = | 21 125 | ( | 168 | + | x | ) |
| 102 | + | x | = | 21 125 | ( | 168 | + | x | ) |
| 102 | + | x | = | 21 125 | × | 168 | + | 21 125 | x |
| 102 | + | x | = | 3528 125 | + | 21 125 | x |
| x | − | 21 125 | x | = | 3528 125 | − | 102 |
104 125 | x | = | 3528 125 | − | 102 |
104 125 | x | = | - | 9222 125 |
| x | = | - | 9222 125 | ÷ | 104 125 |
| = | - | 9222 125 | × | 125 104 |
| = | - | 4611 | × | 1 52 |
| x | = | - | 4611 52 |
| x | = | - 88.673077 |