If a 9 cm long side of the rectangle is reduced by 3 cm, the area is reduced by 9 cm2. What is the area of the trapezoid formed at this time?
把长方形的一条9厘米长的边减少3厘米，面积就减少9平方厘米，这时变成的梯形面积是多少平方厘米？
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">9 * (2/3)</gadget>
<output>6</output>

<gadget id="calculator">9 * 6</gadget>
<output>54</output>

<gadget id="calculator">54 - 9</gadget>
<output>45</output>

<result>45</result>