| 120 | ( | 10000 | ÷ | x | ) | + | 90 | ( | 10000 | ÷ | x | ) | + | 110 | ( | 20000 | ÷ | x | − | 10000 | ÷ | 90 | ) | = | 20000 |
| 120 | × | 10000 | ÷ | x | + | 90 | ( | 10000 | ÷ | x | ) | + | 110 | ( | 20000 | ÷ | x | − | 10000 | ÷ | 90 | ) | = | 20000 |
| 1200000 | ÷ | x | + | 90 | ( | 10000 | ÷ | x | ) | + | 110 | ( | 20000 | ÷ | x | − | 10000 | ÷ | 90 | ) | = | 20000 |
| 方程两边同时乘以: | x |
| 1200000 | + | 90 | ( | 10000 | ÷ | 1 | ) | × | 1 | + | 110 | ( | 20000 | ÷ | x | − | 10000 | ÷ | 90 | ) | x | = | 20000 | x |
| 1200000 | + | 90 | × | 10000 | ÷ | 1 | × | 1 | + | 110 | ( | 20000 | ÷ | x | − | 10000 | ÷ | 90 | ) | x | = | 20000 | x |
| 1200000 | + | 900000 | + | 110 | ( | 20000 | ÷ | x | − | 10000 | ÷ | 90 | ) | x | = | 20000 | x |
| 2100000 | + | 110 | ( | 20000 | ÷ | x | − | 10000 | ÷ | 90 | ) | x | = | 20000 | x |
| 2100000 | + | 110 | × | 20000 | ÷ | x | × | x | − | 110 | × | 10000 | ÷ | 90 | × | x | = | 20000 | x |
| 2100000 | + | 2200000 | ÷ | x | × | x | − | 110000 9 | x | = | 20000 | x |
| - | 110000 9 | x | − | 20000 | x | = | - | 2100000 | − | 2200000 | ÷ | 1 | × | 1 |
| - | 110000 9 | x | − | 20000 | x | = | - | 2100000 | − | 2200000 |
| - | 290000 9 | x | = | - | 2100000 | − | 2200000 |
| - | 290000 9 | x | = | - | 4300000 |
| 4300000 | = | 290000 9 | x |
290000 9 | x | = | 4300000 |
| x | = | 4300000 | ÷ | 290000 9 |
| = | 4300000 | × | 9 290000 |
| = | 430 | × | 9 29 |
| x | = | 3870 29 |
| x | = | 133.448276 |