You are responsible to pay back the following: $400 due today, $500 due in five months, and $618 due in one year. You are given the option: instead of making the above 3 payments, you can pay the same amount as a single payment 9 months from now. Assuming a 12% per annum (p.a) interest rate, how much will the single payment be?

An original payment of $1500 due today is replaced by two equal payments due in 2 and 7 months. Interest rate is 10% p.a. What are the replacement payments?