There are 3 bookshelves in Xiaoying's house, each with 4 floors, and there are 240 books in total. How many books are placed on each floor on average?
小英家有3个书架，每个书架有4层，一共放240本书．平均每层放多少本书？
<gadget id="calculator">240 / 3 / 4</gadget>
<output>20</output>

<result>20</result>