A rectangular iron frame with a length of 8 decimeters and a width of 4 decimeters is taken apart to form a square. What is the side length of this square?
把一个长8分米，宽4分米的长方形铁架，拆开后围成一个正方形，这个正方形的边长是多少？
<gadget id="calculator">8 + 4</gadget>
<output>12</output>

<gadget id="calculator">12 * 2</gadget>
<output>24</output>

<gadget id="calculator">24 / 4</gadget>
<output>6</output>

<result>6</result>