Xiaohong surrounds a rectangle with a length of 12 cm and a width of 8 cm with an iron wire. If this wire surrounds a square, what is the side length of the square in centimeters?
小红用一根铁丝围成一个长12厘米，宽8厘米的长方形，如果用这根铁丝围一个正方形，那么正方形的边长是多少厘米．
<gadget id="calculator">12 + 8</gadget>
<output>20</output>

<gadget id="calculator">2 / 4</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">20 * (1/2)</gadget>
<output>10</output>

<result>10</result>