add up all the x's and distribute them starting from the outside until you get to the middle. if there is an odd number of x's (which there isn't), the last x to be placed will be on the spot that is the median. If there is an even number of x's, and they both land on the same spot, that spot will be the median, and if they are next to each other, themedian will be between them.
Let b be the number of books in a box. Then we can say that the total number of books is equal to the number of boxes times the number of books per box.
