6th grade math proportionally

Aparallel system functions whenever at least one of its components works. consider a parallel system of n components, and suppose each component works independently with probability 0.5. find the conditional probability that component n works given that the system is working

Which of the following answers is 5/25 simplified? 1/5 5/5 2/5 1/25

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 it's length. what is the length of louis's basement