For a trapezoid, if the upper base is extended by 5 cm, the area increases by 25 cm2 and becomes a parallelogram. If the upper base of the original trapezoid is 5 cm, what is the area of the original trapezoid in square centimeters? (Friendly reminder: it will be easier to draw a picture before answering)
一个梯形，如果上底延长5厘米，面积就增加25平方厘米，而且变成了一个平行四边形．如果原梯形的上底是5厘米，那么原梯形的面积是多少平方厘米？(友情提示：先画图再解答会容易些)
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">25 * (2/5)</gadget>
<output>10</output>

<gadget id="calculator">5 + 10</gadget>
<output>15</output>

<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">15 * 5</gadget>
<output>75</output>

<result>75</result>