A rectangle with a length of 12 cm and a width of 9 cm is cut out of the largest square. What is the perimeter of this square in cm?
一个长方形长12厘米，宽9厘米，从中剪出一个最大的正方形，这个正方形的周长是多少厘米．
<gadget id="calculator">9 * 4</gadget>
<output>36</output>

<result>36</result>