Cut the largest square out of a rectangle with a length of 25 cm and a width of 20 cm. What is the perimeter of this square in cm?
在一个长25CM，宽20CM的长方形中剪一个最大的正方形，这个正方形的周长是多少CM．
<gadget id="calculator">20 * 4</gadget>
<output>80</output>

<result>80</result>