Now that they have accumulated a deposit of $50,000, Scott and Helen wish to use the deposit and take out a housing loan to purchase a home. The home costs $600,000. The loan is to be repaid in equal monthly instalments over a term of 30 years.Helen recalls that the interest rate quoted by the bank is an annual nominal rate of 4.80%pa compounded monthly.In 15 years (just after the 180^th repayment has been made), the bank interest rate will change to an annual nominal rate of 4.2%pa compounded monthly.

Q1. How to calculate original monthly repayment

Q2. How much is the monthly repayment after the interest rate cut, assuming Scott and Helen would then wish to repay the loan after a further ten years?