| 1200 | ( | 40 | − | a | ) | + | 24000 | ( | 1 | − | 5 | × | a% | ) | = | 52000 | ( | 1 | + | 5 | × | a% | ) |
| 方程左边 = | 1200 | × | 40 | − | 1200 | a | + | 24000 | ( | 1 | − | 5 | × | a% | ) |
| = | 48000 | − | 1200 | a | + | 24000 | ( | 1 | − | 5 | × | a% | ) |
| = | 48000 | − | 1200 | a | + | 24000 | × | 1 | − | 24000 | × | 5 | × | a% |
| = | 48000 | − | 1200 | a | + | 24000 | − | 1200 | a |
| = | 72000 | − | 2400 | a |
| 72000 | − | 2400 | a | = | 52000 | ( | 1 | + | 5 | × | a% | ) |
| 方程右边 = | 52000 | × | 1 | + | 52000 | × | 5 | × | a% |
| = | 52000 | + | 2600 | a |
| 72000 | − | 2400 | a | = | 52000 | + | 2600 | a |
| - | 2400 | a | − | 2600 | a | = | 52000 | − | 72000 |
| - | 5000 | a | = | 52000 | − | 72000 |
| - | 5000 | a | = | - | 20000 |
| 20000 | = | 5000 | a |
| 5000 | a | = | 20000 |
| a | = | 20000 | ÷ | 5000 |
| = | 20000 | × | 1 5000 |
| = | 4 | × | 1 |
| a | = | 4 |