| ( | a | − | 480 | ) | ÷ | ( | 2 | a | − | 240 | ) | = | 480 | ÷ | ( | a | + | 240 | ) |
| 方程两边同时乘以: | ( | 2 | a | − | 240 | ) | , | ( | a | + | 240 | ) |
| ( | a | − | 480 | ) | ( | a | + | 240 | ) | = | 480 | ( | 2 | a | − | 240 | ) |
| a | ( | a | + | 240 | ) | − | 480 | ( | a | + | 240 | ) | = | 480 | ( | 2 | a | − | 240 | ) |
| a | ( | a | + | 240 | ) | − | 480 | ( | a | + | 240 | ) | = | 480 | × | 2 | a | − | 480 | × | 240 |
| a | ( | a | + | 240 | ) | − | 480 | ( | a | + | 240 | ) | = | 960 | a | − | 115200 |
| a | a | + | a | × | 240 | − | 480 | ( | a | + | 240 | ) | = | 960 | a | − | 115200 |
| a | a | + | 240 | a | − | 480 | a | − | 480 | × | 240 | = | 960 | a | − | 115200 |
| a | a | + | 240 | a | − | 480 | a | − | 115200 | = | 960 | a | − | 115200 |
| a | a | − | 240 | a | − | 115200 | = | 960 | a | − | 115200 |