12 5 | ( | 1 | + | a% | ) | × | 400 | + | 500 | ( | 1 | + | a% | ) | × | 12 5 | ( | 1 | + | a% | ) | = | 21600 | ( | 1 | + | 9 | ÷ | 20 | × | a% | ) |
方程左边 = | 960 | ( | 1 | + | a% | ) | + | 1200 | ( | 1 | + | a% | ) | ( | 1 | + | a% | ) |
960 | ( | 1 | + | a% | ) | + | 1200 | ( | 1 | + | a% | ) | ( | 1 | + | a% | ) | = | 21600 | ( | 1 | + | 9 | ÷ | 20 | × | a% | ) |
方程左边 = | 960 | × | 1 | + | 960 | × | a% | + | 1200 | ( | 1 | + | a% | ) | ( | 1 | + | a% | ) |
= | 960 | + | 48 5 | a | + | 1200 | ( | 1 | + | a% | ) | ( | 1 | + | a% | ) |
= | 960 | + | 48 5 | a | + | 1200 | × | 1 | ( | 1 | + | a% | ) | + | 1200 | × | a% | ( | 1 | + | a% | ) |
= | 960 | + | 48 5 | a | + | 1200 | ( | 1 | + | a% | ) | + | 12 | a | ( | 1 | + | a% | ) |
= | 960 | + | 48 5 | a | + | 1200 | × | 1 | + | 1200 | × | a% | + | 12 | a | ( | 1 | + | a% | ) |
= | 960 | + | 48 5 | a | + | 1200 | + | 12 | a | + | 12 | a | ( | 1 | + | a% | ) |
= | 2160 | + | 108 5 | a | + | 12 | a | ( | 1 | + | a% | ) |
= | 2160 | + | 108 5 | a | + | 12 | a | × | 1 | + | 12 | a | × | a% |
= | 2160 | + | 108 5 | a | + | 12 | a | + | 3 25 | a | a |
= | 2160 | + | 168 5 | a | + | 3 25 | a | a |
2160 | + | 168 5 | a | + | 3 25 | a | a | = | 21600 | ( | 1 | + | 9 | ÷ | 20 | × | a% | ) |
方程右边 = | 21600 | × | 1 | + | 21600 | × | 9 | ÷ | 20 | × | a% |
= | 21600 | + | 486 5 | a |
2160 | + | 168 5 | a | + | 3 25 | a | a | = | 21600 | + | 486 5 | a |