Answer:
There would be 11 books in each stack, to have the same number.
Explanation:
1. Let's review the information given to us to answer the question correctly:
Books in stack 1 = 15
Books in stack 2 = 9
Books in stack 3 = 9
2. If the books were rearranged so that the stack had the same number of books how many books would be even?
Total books = Books in stack 1 + Books in stack 2 + Books in stack 3
Total books = 15 + 9 + 9
Total books = 33
Total books/Number of stacks = Number of books per stack to be the same
33/3 = Number of books per stack to be the same
Number of books per stack to be the same = 11