If the area of a triangle is 28 square decimeters, what is the area of a parallelogram with the same base and height?
一个三角形的面积是28平方分米，与它等底等高的平行四边形的面积是多少．
<gadget id="calculator">28 * 2</gadget>
<output>56</output>

<result>56</result>