| 300 | ( | 1 | + | a% | ) | + | 200 | ( | 1 | + | 3 | × | a% | ) | ( | 1 | − | a% | ) | = | 500 | ( | 1 | + | 29 25 | × | a% | ) |
| 方程左边 = | 300 | × | 1 | + | 300 | × | a% | + | 200 | ( | 1 | + | 3 | × | a% | ) | ( | 1 | − | a% | ) |
| = | 300 | + | 3 | a | + | 200 | ( | 1 | + | 3 | × | a% | ) | ( | 1 | − | a% | ) |
| = | 300 | + | 3 | a | + | 200 | × | 1 | ( | 1 | − | a% | ) | + | 200 | × | 3 | × | a% | ( | 1 | − | a% | ) |
| = | 300 | + | 3 | a | + | 200 | ( | 1 | − | a% | ) | + | 6 | a | ( | 1 | − | a% | ) |
| = | 300 | + | 3 | a | + | 200 | × | 1 | − | 200 | × | a% | + | 6 | a | ( | 1 | − | a% | ) |
| = | 300 | + | 3 | a | + | 200 | − | 2 | a | + | 6 | a | ( | 1 | − | a% | ) |
| = | 500 | + | 1 | a | + | 6 | a | ( | 1 | − | a% | ) |
| = | 500 | + | 1 | a | + | 6 | a | × | 1 | − | 6 | a | × | a% |
| = | 500 | + | 1 | a | + | 6 | a | − | 3 50 | a | a |
| = | 500 | + | 7 | a | − | 3 50 | a | a |
| 500 | + | 7 | a | − | 3 50 | a | a | = | 500 | ( | 1 | + | 29 25 | × | a% | ) |
| 方程右边 = | 500 | × | 1 | + | 500 | × | 29 25 | × | a% |
| = | 500 | + | 29 5 | a |
| 500 | + | 7 | a | − | 3 50 | a | a | = | 500 | + | 29 5 | a |