The normal understanding is that 7.86% is 0.786%, which seems to be the monthly interest rate. Then it will be 9.432% after annualization.
At present, the benchmark annual interest rate for loans over five years is 6.55%, which is only 0.5458% after monthly payment, that is, only 5%.
According to the annual interest rate of 9.432%, the ten-year principal and interest repayment (120) should be 1032.20 yuan per month.
Multiplied by 12 is the annual return, that is,1032.20 *12 =12386.40 yuan.
It is easy to know that 123864 yuan is paid back in ten years, so after deducting the principal of 80,000 yuan, the actual interest is 43864 yuan.