| 5000 | = | ( | p | − | 50 | ) | × | 1800 | − | 50000 |
| 方程右边 = | p | × | 1800 | − | 50 | × | 1800 | − | 50000 |
| = | p | × | 1800 | − | 90000 | − | 50000 |
| = | 1800 | p | − | 140000 |
| 5000 | = | 1800 | p | − | 140000 |
| - | 1800 | p | = | - | 140000 | − | 5000 |
| - | 1800 | p | = | - | 145000 |
| 145000 | = | 1800 | p |
| 1800 | p | = | 145000 |
| p | = | 145000 | ÷ | 1800 |
| = | 145000 | × | 1 1800 |
| = | 725 | × | 1 9 |
| p | = | 725 9 |
| p | = | 80.555556 |