There are 2 bookshelves in Xiaoming's house, each with 4 floors, and there are 240 books in total. How many books are placed on each shelf on average?
小明家有2个书架，每个书架有4层，一共放240本书．平均每个书架每层放多少本书？
<gadget id="calculator">240 / 2 / 4</gadget>
<output>30</output>

<result>30</result>