A rectangle with a perimeter of 20cm, if its length is reduced by 1cm and its width increased by 1cm, then it becomes a square, what is the area of the original rectangle in cm**2.
一个周长为20cm的长方形，如果把它的长减少1cm，宽增加1cm，那么它变成一个正方形，则原长方形的面积是多少cm**2．
<gadget id="calculator">6 * 4</gadget>
<output>24</output>

<result>24</result>