Set up an amortization schedule for a 15000 loan to be

Question

1. Set up an amortization schedule for a $15,000 loan to be repaid in equal installments at the end of each of the next 4 years. The interest rate is 10%.
2. How large must each payment be if the loan is for $30,000? Assume that the interest rate remains at 10% and that the loan is paid off over 4 years.
3. How large must each payment be if the loan is for $30,000, the interest rate is 10%, and the loan is paid off in equal installments at the end of each of the next 8 years? This loan is for the same amount as in part b, but the payments are spread out over twice as many periods. Why are these payments not half as large as the payments on the loan in part b?