| ( | ( | 100 | + | x | ) | ( | 300 | − | 2 | x | ) | ) | ÷ | ( | 100 | ( | 200 | − | x | ) | ) | = | 0 |
| 方程两边同时乘以: | ( | 100 | ( | 200 | − | x | ) | ) |
| ( | ( | 100 | + | x | ) | ( | 300 | − | 2 | x | ) | ) | = | 0 |
| ( | 100 | + | x | ) | ( | 300 | − | 2 | x | ) | = | 0 |
| 100 | ( | 300 | − | 2 | x | ) | + | x | ( | 300 | − | 2 | x | ) | = | 0 |
| 100 | × | 300 | − | 100 | × | 2 | x | + | x | ( | 300 | − | 2 | x | ) | = | 0 |
| 30000 | − | 200 | x | + | x | ( | 300 | − | 2 | x | ) | = | 0 |
| 30000 | − | 200 | x | + | x | × | 300 | − | x | × | 2 | x | = | 0 |
| 30000 | + | 100 | x | − | x | × | 2 | x | = | 0 |