| ( | i | − | 7 100 | ) | ÷ | ( | 8 100 | − | 7 100 | ) | = | 1373 100 |
| 方程两边同时乘以: | ( | 8 100 | − | 7 100 | ) |
| ( | i | − | 7 100 | ) | = | 1373 100 | ( | 8 100 | − | 7 100 | ) |
| i | − | 7 100 | = | 1373 100 | ( | 8 100 | − | 7 100 | ) |
| i | − | 7 100 | = | 1373 100 | × | 8 100 | − | 1373 100 | × | 7 100 |
| i | − | 7 100 | = | 1373 1250 | − | 9611 10000 |
| i | − | 7 100 | = | 1373 10000 |
| i | = | 1373 10000 | + | 7 100 |
| i | = | 2073 10000 |