| 3000 | × | a% | × | 150 | × | 11 10 | + | 5000 | × | 5 100 | × | 96 | ( | 1 | − | 5 | ÷ | 4 | × | a% | ) | = | 117000 |
| 方程左边 = | 4950 | a | + | 24000 | ( | 1 | − | 5 | ÷ | 4 | × | a% | ) |
| 4950 | a | + | 24000 | ( | 1 | − | 5 | ÷ | 4 | × | a% | ) | = | 117000 |
| 方程左边 = | 4950 | a | + | 24000 | × | 1 | − | 24000 | × | 5 | ÷ | 4 | × | a% |
| = | 4950 | a | + | 24000 | − | 300 | a |
| = | 4650 | a | + | 24000 |
| 4650 | a | + | 24000 | = | 117000 |
| 4650 | a | = | 117000 | − | 24000 |
| 4650 | a | = | 93000 |
| a | = | 93000 | ÷ | 4650 |
| = | 93000 | × | 1 4650 |
| = | 20 | × | 1 |
| a | = | 20 |