| 3000 | + | ( | a | + | 21 20 | ) | + | 15 | ( | 1 | + | a | ) | = | 51750 | + | 15 |
| 方程左边 = | 3000 | + | a | + | 21 20 | + | 15 | ( | 1 | + | a | ) |
| = | 60021 20 | + | a | + | 15 | ( | 1 | + | a | ) |
| = | 60021 20 | + | a | + | 15 | × | 1 | + | 15 | a |
| = | 60021 20 | + | a | + | 15 | + | 15 | a |
| = | 60321 20 | + | 16 | a |
60321 20 | + | 16 | a | = | 51750 | + | 15 |
| 方程右边 = | 51765 |
60321 20 | + | 16 | a | = | 51765 |
| 16 | a | = | 51765 | − | 60321 20 |
| 16 | a | = | 974979 20 |
| a | = | 974979 20 | ÷ | 16 |
| = | 974979 20 | × | 1 16 |
| a | = | 974979 320 |
| a | = | 3046.809375 |