Present Valnes. Compute the peesent value of a $$100$ cash flow for the following combinations of discount rates and times $($B$)($O$2)$

a$.r=8\%,t=10$ years

b$.r=8\%,t=20$ years

c$.r=4\%,t=10$ years

d$.r=4\%,t=20$ years

Future Vahues. Compute the future value of a $$100$ cash flow for the same combinations of rates and tuates as in problem $1.(13)$ LO$1)$