For a parallelogram, if the base is increased by 2 decimeters and the height remains the same, the area will increase by 6 decimeters; if the height is increased by 1 decimeter and the base remains the same, the area will be increased by 4 decimeters. What is the area of the original parallelogram?
一个平行四边形，若底增加2分米，高不变，则面积增加6平方分米；若高增加1分米，底不变，则面积增加4平方分米．原平行四边形的面积是多少？
<gadget id="calculator">4 / 1</gadget>
<output>4</output>

<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">4 * 3</gadget>
<output>12</output>

<result>12</result>