| 125000 | − | ( | 400 | ( | 1 | − | a% | ) | × | 200 | ( | 1 | + | a% | ) | + | 150 | × | 3 4 | × | a% | ) | = | 8750 |
| 方程左边 = | 125000 | − | 400 | ( | 1 | − | a% | ) | × | 200 | ( | 1 | + | a% | ) | − | 150 | × | 3 4 | × | a% |
| = | 125000 | − | 80000 | ( | 1 | − | a% | ) | ( | 1 | + | a% | ) | − | 9 8 | a |
| = | 125000 | − | 80000 | × | 1 | ( | 1 | + | a% | ) | + | 80000 | × | a% | ( | 1 | + | a% | ) | − | 9 8 | a |
| = | 125000 | − | 80000 | ( | 1 | + | a% | ) | + | 800 | a | ( | 1 | + | a% | ) | − | 9 8 | a |
| = | 125000 | − | 80000 | × | 1 | − | 80000 | × | a% | + | 800 | a | ( | 1 | + | a% | ) | − | 9 8 | a |
| = | 125000 | − | 80000 | − | 800 | a | + | 800 | a | ( | 1 | + | a% | ) | − | 9 8 | a |
| = | 45000 | − | 6409 8 | a | + | 800 | a | ( | 1 | + | a% | ) |
| = | 45000 | − | 6409 8 | a | + | 800 | a | × | 1 | + | 800 | a | × | a% |
| = | 45000 | − | 6409 8 | a | + | 800 | a | + | 8 | a | a |
| = | 45000 | − | 9 8 | a | + | 8 | a | a |
| 45000 | − | 9 8 | a | + | 8 | a | a | = | 8750 |