Li Cong received a batch of birthday presents—books, among which Chinese books are twice as many as foreign language books, and foreign language books are 27 fewer than twice as many Chinese books. How many books are there in total?
李聪得到一批生日礼物--图书，其中中文图书是外语图书的2倍，而外语图书比中文图书的2倍少27本．这批图书共有多少本．
<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<gadget id="calculator">4 - 1</gadget>
<output>3</output>

<gadget id="calculator">27 / 3</gadget>
<output>9</output>

<gadget id="calculator">9 * 2</gadget>
<output>18</output>

<gadget id="calculator">9 + 18</gadget>
<output>27</output>

<result>27</result>