| ( | 21 | ( | 12 | + | x | ) | ) | ÷ | ( | 25 | ( | 21 | + | x | ) | ) | = | 151 250 |
| 方程两边同时乘以: | ( | 25 | ( | 21 | + | x | ) | ) |
| ( | 21 | ( | 12 | + | x | ) | ) | = | 151 250 | ( | 25 | ( | 21 | + | x | ) | ) |
| 21 | ( | 12 | + | x | ) | = | 151 250 | ( | 25 | ( | 21 | + | x | ) | ) |
| 21 | ( | 12 | + | x | ) | = | 151 250 | × | 25 | ( | 21 | + | x | ) |
| 21 | ( | 12 | + | x | ) | = | 151 10 | ( | 21 | + | x | ) |
| 21 | × | 12 | + | 21 | x | = | 151 10 | ( | 21 | + | x | ) |
| 21 | × | 12 | + | 21 | x | = | 151 10 | × | 21 | + | 151 10 | x |
| 252 | + | 21 | x | = | 3171 10 | + | 151 10 | x |
| 21 | x | − | 151 10 | x | = | 3171 10 | − | 252 |
59 10 | x | = | 3171 10 | − | 252 |
59 10 | x | = | 651 10 |
| x | = | 651 10 | ÷ | 59 10 |
| = | 651 10 | × | 10 59 |
| = | 651 | × | 1 59 |
| x | = | 651 59 |
| x | = | 11.033898 |