If the length of a rectangle is increased by 4 meters, the area will increase by 20 square meters; if the width of the original rectangle is increased by 4 meters, the area will increase by 32 square meters. What is the area of the original rectangle in square meters?
一个长方形，如果长增加4米，面积就增加20平方米；如果原长方形宽增加4米，面积就增加32平方米．原长方形的面积是多少平方米．
<gadget id="calculator">20 / 4</gadget>
<output>5</output>

<gadget id="calculator">32 / 4</gadget>
<output>8</output>

<gadget id="calculator">5 * 8</gadget>
<output>40</output>

<result>40</result>