When she woke up in the morning, Xixi tidied up her bookcase. She found that there were 28 books on the first floor of the bookcase, and if there were 8 more books, it would be twice the number of books on the second floor. Ask Xixi how many books are on the second floor of the bookcase? (column equation solution)
早晨一起来，熙熙就整理自己的书柜．她发现书柜第一层有28本书，如果再放8本，就是第二层书本数的2倍．问熙熙在书柜的第二层放了多少本书？(列方程解答)
<gadget id="calculator">28 + 8</gadget>
<output>36</output>

<gadget id="calculator">36 / 2</gadget>
<output>18</output>

<result>18</result>