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]