The area of a parallelogram formed by two identical triangular plates is 18 square decimeters, what is the area of each triangular plate?
用两块完全一样的三角板拼成的平行四边形的面积是18平方分米，每块三角板的面积是多少平方分米．
<gadget id="calculator">18 / 2</gadget>
<output>9</output>

<result>9</result>