rectangle with a length of 50 meters and a width of 30 centimeters is formed by a piece of iron wire. Now change it into a square, what is the side length of this square?
用一根系铁丝围成一个长方形，长50米，宽30厘米．现在把它改围成一个正方形，这个正方形的边长是多少厘米？
<gadget id="calculator">50 + 30</gadget>
<output>80</output>

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

<gadget id="calculator">80 * (1/2)</gadget>
<output>40</output>

<result>40</result>