a$.$ $$10,000$ invested for $5$ years with simple annual interest of $10\%$ would have a future value of

b$.$ $$10,000$ invested for $5$ years at $10\%,$ compounded annually has a future value of

c$.$ Present value of a future payment of $$5,000$ at the end of year three when interest rates are $4\mathrm{.}5\%$

d$.$ When interest rates are at $4\%,$ which would be better, taking $$30,000$ today, or $$36,000$ in four years? Show calculations.