Suppose you receive $100 at the end of each year for the next three years

a) Computation of Present Value of Cash Flows:

Present Value of Cash Flows = P*[1-(1/(1+r)^n)]/r

Here,

P = Cash Flows = $100

r = 8%

n = 3 years 

Present Value of Cash Flows = $100*[1-(1/(1+8%)^3)]/8% = $257.71

b) Computation of Future Value:

Future Value = Present Value*(1+Rate)^Time

= $257.71*(1+8%)^3

Future Value = $324.64

c) 

Year 1

Balance at end = $100

Year 2

Balance at end = $100 * 1.08 (the $100 above would earn interest) + $100 = $208

Year 3

Balance at end = $208 * 1.08 + $100 = $324.64 (same as in B because we are discounting and then compounding with the same interest rate).