A parallelogram orchard whose height is 40 meters and twice the base, what is the area in square meters?
一个平行四边形的果园，它的高是40米，是底的2倍，面积是多少平方米．
<gadget id="calculator">40 / 2</gadget>
<output>20</output>

<gadget id="calculator">20 * 40</gadget>
<output>800</output>

<result>800</result>