If the loan principal is: 300,000, the term is: 20 years, according to the People’s Bank of China’s benchmark annual interest rate for loans with a term of more than 5 years: 4.90 (under unchanged conditions), the equal principal and interest repayment method is used, and the monthly payment is: 1963.33 , total repayment: 471199.72, total interest: 171199.72.