| ( | 450 | − | 20000 | ÷ | ( | x | + | 52 5 | ) | ) | x | = | 40000 |
| 450 | x | − | 20000 | ÷ | ( | x | + | 52 5 | ) | × | x | = | 40000 |
| 方程两边同时乘以: | ( | x | + | 52 5 | ) |
| 450 | x | ( | x | + | 52 5 | ) | − | 20000 | x | = | 40000 | ( | x | + | 52 5 | ) |
| 450 | x | x | + | 450 | x | × | 52 5 | − | 20000 | x | = | 40000 | ( | x | + | 52 5 | ) |
| 450 | x | x | + | 450 | x | × | 52 5 | − | 20000 | x | = | 40000 | x | + | 40000 | × | 52 5 |
| 450 | x | x | + | 4680 | x | − | 20000 | x | = | 40000 | x | + | 416000 |
| 450 | x | x | − | 15320 | x | = | 40000 | x | + | 416000 |