After the width of a rectangle is increased by 4 cm, it becomes a square. At this time, the area is increased by 200 cm2. Find the area of the original rectangle.
一个长方形的宽增加4厘米后，变成了正方形，这时面积增加了200平方厘米，求原来长方形的面积．
<gadget id="calculator">200 / 4</gadget>
<output>50</output>

<gadget id="calculator">50 - 4</gadget>
<output>46</output>

<gadget id="calculator">46 * 50</gadget>
<output>2_300</output>

<result>2_300</result>