The height of a trapezoid is 18 cm. If the upper base is extended by 12 cm, it becomes exactly a parallelogram with an area of 360 cm2. What is the area of the original trapezoid in cm2?
一个梯形的高是18厘米，如果将上底延长12厘米，恰好变成一个面积是360平方厘米的平行四边形，原来梯形的面积是多少平方厘米．
<gadget id="calculator">18 / 2</gadget>
<output>9</output>

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

<gadget id="calculator">360 - 108</gadget>
<output>252</output>

<result>252</result>