| 10000 | ( | 12 | − | 2 | p | ) | = | 20 | p | × | 1000 |
| 方程左边 = | 10000 | × | 12 | − | 10000 | × | 2 | p |
| = | 120000 | − | 20000 | p |
| 120000 | − | 20000 | p | = | 20 | p | × | 1000 |
| 方程右边 = | 20000 | p |
| 120000 | − | 20000 | p | = | 20000 | p |
| - | 20000 | p | − | 20000 | p | = | - | 120000 |
| - | 40000 | p | = | - | 120000 |
| 120000 | = | 40000 | p |
| 40000 | p | = | 120000 |
| p | = | 120000 | ÷ | 40000 |
| = | 120000 | × | 1 40000 |
| = | 3 | × | 1 |
| p | = | 3 |