A triangle and a parallelogram have the same base and height. If the area of the parallelogram is 20 square decimeters, what is the area of the triangle?
三角形和平行四边形等底等高，如果平行四边形面积是20平方分米，则三角形的面积是多少．
<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<result>10</result>