Need help quick time is passing

Determine the fraction of total interest owed. after the fourth month of a 12-month loan: the numerator is: {(n + ) + (n + ) + (n + ) + (n + )} = , and the denominator is: {(n) + (n + 1) + + (n + )} = . therefore, the fraction is numerator/denominator (to the nearest tenth) =

Any is very appreciated! (picture is provided below)not sure how to do this at all won't lie

An octagonal prism has jow many lateral faces?