| ( | a | × | 20 100 | + | ( | a | × | 20 100 | + | a | ) | ) | × | 20 100 | = | 171000 |
| 方程左边 = | a | × | 20 100 | × | 20 100 | + | ( | a | × | 20 100 | + | a | ) | × | 20 100 |
| = | a | × | 1 25 | + | ( | a | × | 20 100 | + | a | ) | × | 20 100 |
| = | 1 25 | a | + | a | × | 20 100 | × | 20 100 | + | a | × | 20 100 |
| = | 1 25 | a | + | a | × | 1 25 | + | a | × | 20 100 |
| = | 7 25 | a |
7 25 | a | = | 171000 |
| a | = | 171000 | ÷ | 7 25 |
| = | 171000 | × | 25 7 |
| a | = | 4275000 7 |
| a | = | 610714.285714 |