A piece of iron wire can form a square with an area of 49 square centimeters. If it forms a rectangle with a width of 4 centimeters, find the area of the rectangle.
一根铁丝，可围成面积是49平方厘米的正方形，如果围成宽是4厘米的长方形，求长方形的面积．
<gadget id="calculator">7 * 4</gadget>
<output>28</output>

<gadget id="calculator">28 / 2</gadget>
<output>14</output>

<gadget id="calculator">14 - 4</gadget>
<output>10</output>

<gadget id="calculator">10 * 4</gadget>
<output>40</output>

<result>40</result>