Answer:
The data we have is:
Library A charges $96 per year.
Library B charges $3 per book he borrows.
Let's find the number of books X that he needs to borrow in order to spend the same amount in each library:
$3*X = $96
X = 96/3 = 32.
This means that if Aaden borrows 32 books per year, is the same for him if he chooses library A or B.
If he borrows more than 32 books per year, library A will be cheaper. (if he borrows 33 books, library B costs 33*$3 = $99, which is larger than the $96 of library A)
If he borrows less than 32 books per year, library B will be cheaper. (if he borrows 31 books library B costs $3*31 = $93, which is cheaper than the$96 of library A)