The length of a rectangle is 9 centimeters. If one side of the rectangle is reduced by 3 centimeters and the other side remains the same, the area is reduced by 9 square centimeters. What is the area of the trapezoid formed at this time?
一个长方形的长为9厘米，把它的长的一边减少3厘米，另一边不变，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>