The lower base of a trapezoid is 24 centimeters. If its upper base is extended by 9 centimeters, it becomes a parallelogram, and the area increases by 36 square centimeters. What is the area of the original trapezoid in square centimeters?
一个梯形的下底是24厘米，把它的上底延长9厘米，就变成一个平行四边形，这时面积增加36平方厘米．原来梯形的面积是多少平方厘米．
<gadget id="calculator">24 - 9</gadget>
<output>15</output>

<gadget id="calculator">24 + 15</gadget>
<output>39</output>

<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">36 * (2/9)</gadget>
<output>8</output>

<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">39 * 4</gadget>
<output>156</output>

<result>156</result>