The upper base of a right-angled trapezoid is 6 cm. If the upper base is extended by 4 cm, the original trapezoid becomes a square. What is the area of the original trapezoid?
一个直角梯形的上底为6厘米，如果把上底延长4厘米，原来的梯形变成了正方形，原来的梯形面积是多少．
<gadget id="calculator">6 + 4</gadget>
<output>10</output>

<gadget id="calculator">6 + 10</gadget>
<output>16</output>

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

<gadget id="calculator">16 * 5</gadget>
<output>80</output>

<result>80</result>