There are 126 books in the library, which are placed on 3 shelves on average, and each shelf has 6 floors. On average, how many books are placed on each floor.
图书馆共有126本书，平均放在3个书架上，每个书架有6层．平均每层放几本．
<gadget id="calculator">126 / 3 / 6</gadget>
<output>7</output>

<result>7</result>