The annual loan interest rate =5. 1%, and the monthly interest rate = annual interest rate/12 = 0.425%;

Formula: monthly repayment amount = loan amount * monthly interest rate/1-( 1+ monthly interest rate)-repayment months.

Monthly repayment amount = 420000 * 0.425%/1-(1+0.425%)-360

Monthly repayment amount = 2280.39 yuan

Total repayment = 820,940.06 yuan.

Total interest = 400,940.06 yuan

Answer:

Under the assumed conditions, the monthly repayment amount of this loan is 2280.39 yuan; The total repayment amount is 820,940.06 yuan; The total interest is 400,940.06 yuan.