The length of a rectangle is 18 cm, which is 3 times the width, find the perimeter of the rectangle.
一个长方形的长是18厘米，是宽的3倍，求这个长方形的周长．
<gadget id="calculator">18 / 3</gadget>
<output>6</output>

<gadget id="calculator">18 + 6</gadget>
<output>24</output>

<gadget id="calculator">24 * 2</gadget>
<output>48</output>

<result>48</result>