Use 20 decimeters of iron wire to form a rectangular frame, so that the length is 4 times the width. What is the area of the rectangle surrounded by square decimeters?
用20分米长的铁丝围成一个长方形框架，使长是宽的4倍，围成的长方形的面积是多少平方分米？
<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">20 / 2 / 5</gadget>
<output>2</output>

<gadget id="calculator">2 * 4</gadget>
<output>8</output>

<gadget id="calculator">2 * 8</gadget>
<output>16</output>

<result>16</result>