If the length of a rectangle is 9 cm and its width is 3 times, what is its perimeter in cm?
一个长方形长9厘米，是宽的3倍，它的周长是多少厘米．
<gadget id="calculator">9 / 3</gadget>
<output>3</output>

<gadget id="calculator">3 + 9</gadget>
<output>12</output>

<gadget id="calculator">12 * 2</gadget>
<output>24</output>

<result>24</result>