For a 8-year loan of $30,000 with an interest rate of 12% compounded monthly,

1. What is your monthly payment?
2. What is the effective annual interest rate?
3. What is the effective monthly interest rate?
4. If I dont make any payment for two years (assuming no penalties) and pay off the entire loan at the end of the second year, what amount do I need to pay?
5. What is the economic equivalent value of $30,000 at this interest rate in 15 months

I have gotten parts 1-3 correct so I don't need help on those, however I cannot find out where I went wrong on part four and I have no idea where to start on part 5

My work is shown here, I hope it is legible enough