| ( | x | + | 20 | ) | ÷ | x | − | 3 | ( | x | + | 20 | ) | ÷ | ( | x | + | 45 | ) | = | 1 |
| 方程两边同时乘以: | x |
| ( | x | + | 20 | ) | − | 3 | ( | x | + | 20 | ) | ÷ | ( | x | + | 45 | ) | × | x | = | 1 | x |
| x | + | 20 | − | 3 | ( | x | + | 20 | ) | ÷ | ( | x | + | 45 | ) | × | x | = | 1 | x |
| 方程两边同时乘以: | ( | x | + | 45 | ) |
| x | ( | x | + | 45 | ) | + | 20 | ( | x | + | 45 | ) | − | 3 | ( | x | + | 20 | ) | x | = | 1 | x | ( | x | + | 45 | ) |
| x | x | + | x | × | 45 | + | 20 | ( | x | + | 45 | ) | − | 3 | ( | x | + | 20 | ) | x | = | 1 | x | ( | x | + | 45 | ) |
| x | x | + | x | × | 45 | + | 20 | ( | x | + | 45 | ) | − | 3 | ( | x | + | 20 | ) | x | = | 1 | x | x | + | 1 | x | × | 45 |
| x | x | + | x | × | 45 | + | 20 | ( | x | + | 45 | ) | − | 3 | ( | x | + | 20 | ) | x | = | 1 | x | x | + | 45 | x |
| x | x | + | 45 | x | + | 20 | x | + | 20 | × | 45 | − | 3 | ( | x | + | 20 | ) | x | = | 1 | x | x | + | 45 | x |
| x | x | + | 45 | x | + | 20 | x | + | 900 | − | 3 | ( | x | + | 20 | ) | x | = | 1 | x | x | + | 45 | x |
| x | x | + | 65 | x | + | 900 | − | 3 | ( | x | + | 20 | ) | x | = | 1 | x | x | + | 45 | x |
| x | x | + | 65 | x | + | 900 | − | 3 | x | x | − | 3 | × | 20 | x | = | 1 | x | x | + | 45 | x |
| x | x | + | 65 | x | + | 900 | − | 3 | x | x | − | 60 | x | = | 1 | x | x | + | 45 | x |
| x | x | + | 5 | x | + | 900 | − | 3 | x | x | = | 1 | x | x | + | 45 | x |