For those of you that might have access to the book, it is

"Discrete Mathematics with Graph Theory" 3e By Goodaire.

I'm kind of stumped on what question 5.20 is asking. In short, we have the symmetric difference of A_1 to A_n, and when n>=3, we know that the solution is A_1 to A_n (symmetric difference of) = (A_1 to A_n-1) symmetrically added to A_n.

We want to inductively prove that it is an odd number of sets for when n>=2.

I'm not sure if this made much sense, but having the textbook would help.

Thank you to all whom help!