| ( | 2900 | − | a | ) | + | ( | 3200 | − | a | ÷ | 2 | ) | + | ( | 3500 | − | a | ÷ | 4 | ) | + | ( | 3500 | − | a | ÷ | 8 | ) | = | 9000 |
| 方程左边 = | 2900 | − | a | + | ( | 3200 | − | a | ÷ | 2 | ) | + | ( | 3500 | − | a | ÷ | 4 | ) | + | ( | 3500 | − | a | ÷ | 8 | ) |
| = | 2900 | − | a | + | 3200 | − | a | ÷ | 2 | + | ( | 3500 | − | a | ÷ | 4 | ) | + | ( | 3500 | − | a | ÷ | 8 | ) |
| = | 6100 | − | 3 2 | a | + | ( | 3500 | − | a | ÷ | 4 | ) | + | ( | 3500 | − | a | ÷ | 8 | ) |
| = | 6100 | − | 3 2 | a | + | 3500 | − | a | ÷ | 4 | + | ( | 3500 | − | a | ÷ | 8 | ) |
| = | 9600 | − | 7 4 | a | + | ( | 3500 | − | a | ÷ | 8 | ) |
| = | 9600 | − | 7 4 | a | + | 3500 | − | a | ÷ | 8 |
| = | 13100 | − | 15 8 | a |
| 13100 | − | 15 8 | a | = | 9000 |
| - | 15 8 | a | = | 9000 | − | 13100 |
| - | 15 8 | a | = | - | 4100 |
| 4100 | = | 15 8 | a |
15 8 | a | = | 4100 |
| a | = | 4100 | ÷ | 15 8 |
| = | 4100 | × | 8 15 |
| = | 820 | × | 8 3 |
| a | = | 6560 3 |
| a | = | 2186.666667 |