Simplify each expression for x=6

Hello people, i have a math question that i need with, me, i will give the correct one brainiest, and for the other correct people, a and 5 stars.

Which recursive formula can be used to determine the total amount of money earned in any year based on the amount earned in the previous year? f(n+1)=f(n)+5

Louis wants to carpet the rectangular floor of his basement the basement has an area of 864 square feet the width of the basement is 2/3 its length what is the length of lewis's basement