Any increase in the length of a side of a square in centimeters increases the perimeter of the square by 20 centimeters.
一个正方形的边长增加多少厘米，就可以使这个正方形的周长增加20厘米．
<gadget id="calculator">20 / 4</gadget>
<output>5</output>

<result>5</result>