| ( | 2900 | − | a | ) | + | ( | 4400 | − | a | ÷ | 2 | ) | + | ( | 5000 | − | a | ÷ | 4 | ) | + | ( | 5000 | − | a | ÷ | 8 | ) | = | 8000 |
| 方程左边 = | 2900 | − | a | + | ( | 4400 | − | a | ÷ | 2 | ) | + | ( | 5000 | − | a | ÷ | 4 | ) | + | ( | 5000 | − | a | ÷ | 8 | ) |
| = | 2900 | − | a | + | 4400 | − | a | ÷ | 2 | + | ( | 5000 | − | a | ÷ | 4 | ) | + | ( | 5000 | − | a | ÷ | 8 | ) |
| = | 7300 | − | 3 2 | a | + | ( | 5000 | − | a | ÷ | 4 | ) | + | ( | 5000 | − | a | ÷ | 8 | ) |
| = | 7300 | − | 3 2 | a | + | 5000 | − | a | ÷ | 4 | + | ( | 5000 | − | a | ÷ | 8 | ) |
| = | 12300 | − | 7 4 | a | + | ( | 5000 | − | a | ÷ | 8 | ) |
| = | 12300 | − | 7 4 | a | + | 5000 | − | a | ÷ | 8 |
| = | 17300 | − | 15 8 | a |
| 17300 | − | 15 8 | a | = | 8000 |
| - | 15 8 | a | = | 8000 | − | 17300 |
| - | 15 8 | a | = | - | 9300 |
| 9300 | = | 15 8 | a |
15 8 | a | = | 9300 |
| a | = | 9300 | ÷ | 15 8 |
| = | 9300 | × | 8 15 |
| = | 620 | × | 8 |
| a | = | 4960 |