The sum of the length and width of a rectangle is 80 cm and its perimeter is equal to the perimeter of a square. What is the area of this square in square centimeters?
一个长方形的长和宽的和是80厘米，它的周长和一个正方形的周长相等．这个正方形的面积是多少平方厘米？
<gadget id="calculator">80 / 2</gadget>
<output>40</output>

<gadget id="calculator">40 * 40</gadget>
<output>1_600</output>

<result>1_600</result>