252 500 | = | 10 100 | + | r | × | 2 | + | 10 100 | r | × | 2 |
| 方程右边 = | 10 100 | + | r | × | 2 | + | 1 5 | r |
| = | 10 100 | + | 11 5 | r |
252 500 | = | 10 100 | + | 11 5 | r |
| - | 11 5 | r | = | 10 100 | − | 252 500 |
| - | 11 5 | r | = | - | 101 250 |
101 250 | = | 11 5 | r |
11 5 | r | = | 101 250 |
| r | = | 101 250 | ÷ | 11 5 |
| = | 101 250 | × | 5 11 |
| = | 101 50 | × | 1 11 |
| r | = | 101 550 |
| r | = | 0.183636 |