The upper base of a trapezoid is 12 cm. If the upper base is extended by 1 cm, it becomes a parallelogram with an area increased by 36 cm2. What is the area of the original trapezoid?
一个梯形的上底是12厘米，如果上底延长1厘米，就成为一个平行四边形，面积比原来增加36平方厘米．原来梯形的面积是多少？
<gadget id="calculator">12 - 1</gadget>
<output>11</output>

<gadget id="calculator">12 + 11</gadget>
<output>23</output>

<gadget id="calculator">2 / 1</gadget>
<output>2</output>

<gadget id="calculator">36 * 2</gadget>
<output>72</output>

<gadget id="calculator">72 / 2</gadget>
<output>36</output>

<gadget id="calculator">23 * 36</gadget>
<output>828</output>

<result>828</result>