There is a rectangle, if the width remains the same, the length increases by 4 meters, the area increases by 24 square meters; if the length remains the same, the width increases by 3 meters, the area increases by 36 square meters, find the area of the original rectangle.
有一个长方形，如果宽不变，长增加4米，面积就增加24平方米；如果长不变，宽增加3米，面积就增加36平方米，求原来长方形的面积．
<gadget id="calculator">36 / 3</gadget>
<output>12</output>

<gadget id="calculator">24 / 4</gadget>
<output>6</output>

<gadget id="calculator">12 * 6</gadget>
<output>72</output>

<result>72</result>