| a | ÷ | 240 | − | 1 2 | = | a | ÷ | ( | 240 | × | 4 | ) | + | 3 | a | ÷ | ( | 288 | × | 4 | ) |
| 方程两边同时乘以: | ( | 240 | × | 4 | ) |
| a | ÷ | 240 | × | ( | 240 | × | 4 | ) | − | 1 2 | ( | 240 | × | 4 | ) | = | a | + | 3 | a | ÷ | ( | 288 | × | 4 | ) | × | ( | 240 | × | 4 | ) |
| a | ÷ | 240 | × | 240 | × | 4 | − | 1 2 | ( | 240 | × | 4 | ) | = | a | + | 3 | a | ÷ | ( | 288 | × | 4 | ) | × | ( | 240 | × | 4 | ) |
| a | ÷ | 240 | × | 240 | × | 4 | − | 1 2 | ( | 240 | × | 4 | ) | = | a | + | 3 | a | ÷ | ( | 288 | × | 4 | ) | × | 240 | × | 4 |
| a | × | 4 | − | 1 2 | ( | 240 | × | 4 | ) | = | a | + | 2880 | a | ÷ | ( | 288 | × | 4 | ) |
| 方程两边同时乘以: | ( | 288 | × | 4 | ) |
| 4 | a | ( | 288 | × | 4 | ) | − | 1 2 | ( | 240 | × | 4 | ) | ( | 288 | × | 4 | ) | = | a | ( | 288 | × | 4 | ) | + | 2880 | a |
| 4 | a | × | 288 | × | 4 | − | 1 2 | ( | 240 | × | 4 | ) | ( | 288 | × | 4 | ) | = | a | ( | 288 | × | 4 | ) | + | 2880 | a |
| 4 | a | × | 288 | × | 4 | − | 1 2 | ( | 240 | × | 4 | ) | ( | 288 | × | 4 | ) | = | a | × | 288 | × | 4 | + | 2880 | a |
| 4608 | a | − | 1 2 | ( | 240 | × | 4 | ) | ( | 288 | × | 4 | ) | = | a | × | 1152 | + | 2880 | a |
| 4608 | a | − | 1 2 | ( | 240 | × | 4 | ) | ( | 288 | × | 4 | ) | = | 4032 | a |
| 4608 | a | − | 1 2 | × | 240 | × | 4 | ( | 288 | × | 4 | ) | = | 4032 | a |
| 4608 | a | − | 480 | ( | 288 | × | 4 | ) | = | 4032 | a |
| 4608 | a | − | 480 | × | 288 | × | 4 | = | 4032 | a |
| 4608 | a | − | 552960 | = | 4032 | a |
| 4608 | a | − | 4032 | a | = | 552960 |
| 576 | a | = | 552960 |
| a | = | 552960 | ÷ | 576 |
| = | 552960 | × | 1 576 |
| = | 960 | × | 1 |
| a | = | 960 |