There is a rectangle, if the length is extended by 12 cm or the width is extended by 9 cm, then the area is increased by 72 square centimeters, what is the area of the original rectangle in square centimeters?
有一个长方形，如果将长延长12厘米或宽延长9厘米，那么面积都增加72平方厘米，原来长方形的面积是多少平方厘米．
<gadget id="calculator">72 / 12</gadget>
<output>6</output>

<gadget id="calculator">72 / 9</gadget>
<output>8</output>

<gadget id="calculator">6 * 8</gadget>
<output>48</output>

<result>48</result>