The lower base of a trapezoid is twice the upper base, and the upper base is extended by 6 cm to form a parallelogram with an area of 144 cm. What is the area of the trapezoid?
一个梯形的下底是上底的2倍，把上底延长6厘米，恰好组成一个面积是144厘米的平行四边形，这个梯形的面积是多少．
<gadget id="calculator">144 / 12</gadget>
<output>12</output>

<gadget id="calculator">6 + 12</gadget>
<output>18</output>

<gadget id="calculator">18 / 2</gadget>
<output>9</output>

<gadget id="calculator">12 * 9</gadget>
<output>108</output>

<result>108</result>