For a parallelogram, if the base is increased by 3 cm, the height remains the same, and the area increases by 12 cm2; if the height is increased by 2 cm, the base remains unchanged, and the area increases by 36 cm2, find the area of the original parallelogram.
一个平行四边形，如底增加3厘米，高不变，面积增加12平方厘米，如高增加2厘米，底不变，面积增加36平方厘米，求原来平行四边形面积．
<gadget id="calculator">12 / 3</gadget>
<output>4</output>

<gadget id="calculator">36 / 2</gadget>
<output>18</output>

<gadget id="calculator">4 * 18</gadget>
<output>72</output>

<result>72</result>