| ( | 9 | + | x | ) | ÷ | ( | 19 | + | x | ) | = | 11 20 |
| 方程两边同时乘以: | ( | 19 | + | x | ) |
| ( | 9 | + | x | ) | = | 11 20 | ( | 19 | + | x | ) |
| 9 | + | x | = | 11 20 | ( | 19 | + | x | ) |
| 9 | + | x | = | 11 20 | × | 19 | + | 11 20 | x |
| 9 | + | x | = | 209 20 | + | 11 20 | x |
| x | − | 11 20 | x | = | 209 20 | − | 9 |
9 20 | x | = | 209 20 | − | 9 |
9 20 | x | = | 29 20 |
| x | = | 29 20 | ÷ | 9 20 |
| = | 29 20 | × | 20 9 |
| = | 29 | × | 1 9 |
| x | = | 29 9 |
| x | = | 3.222222 |