What is the area of the largest parallelogram cut out of a trapezoid whose upper base is 7 decimeters, lower base is 10 decimeters, and height is 5 decimeters?
在一个上底是7分米，下底是10分米，高是5分米的梯形中剪出一个最大的平行四边形的面积是多少平方分米．
<gadget id="calculator">7 * 5</gadget>
<output>35</output>

<result>35</result>