A trapezoid, the upper base is the lower base (2/3), and the upper base is extended by 4 cm to form a parallelogram with an area of 108 square centimeters. How many square centimeters does the area of the parallelogram increase from the original trapezoid? ．
一个梯形，上底是下底的(2/3)，把上底延长4厘米，就成了一个平行四边形，面积是108平方厘米，这个平行四边形的面积比原来梯形的面积增加了多少平方厘米．
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 - (2/3)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">4 / (1/3)</gadget>
<output>12</output>

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

<gadget id="calculator">9 / 2</gadget>
<output>9/2 = around 4.5</output>

<gadget id="calculator">4 * (9/2)</gadget>
<output>18</output>

<result>18</result>