The length of the rectangle is 18 cm and the width is half the length. What is the perimeter of the rectangle?
长方形的长是18厘米，宽是长的一半，长方形的周长是多少？
<gadget id="calculator">18 / 2</gadget>
<output>9</output>

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

<gadget id="calculator">27 * 2</gadget>
<output>54</output>

<result>54</result>