A square is surrounded by an iron wire, and the side length is 7 decimeters. If this iron wire is used to form a rectangle, what is the perimeter of the rectangle?
用一根铁丝围成一个正方形，边长是7分米，如果把这根铁丝围成一个长方形，这个长方形的周长是多少分米．
<gadget id="calculator">7 * 4</gadget>
<output>28</output>

<result>28</result>