Leo borrows $300,000 mortgage to buy a house at the annual interest rate 6.25%.Leo needs to return the ammortized loan with the equal amount of monthly payment. How much is the monthly payment?[A] At the end of the 13th month Leo wants to pay off the mortgage earlier. After Leo paid the 13th month annuity, how much principal Leo has to pay? [B]In which month, the proportion of the interest payment becomes less than 50%?[C] Please key in the procedure of the computation [D]