The school library bought 240 books and put them on 2 bookshelves, each with 4 floors. How many books are placed on each floor on average?
学校图书馆买来240本书，放在2个书架上，每个书架上有4层．平均每层放多少本书？
<gadget id="calculator">2 * 4</gadget>
<output>8</output>

<gadget id="calculator">240 / 8</gadget>
<output>30</output>

<result>30</result>