If you fold a rectangle with a perimeter of 18 cm and a width of 4 cm into a largest square, what is the side length of this square in cm?
把周长是18厘米、宽是4厘米的长方形折成一个最大的正方形，这个正方形的边长是多少厘米．
<gadget id="calculator">18 + 4</gadget>
<output>22</output>

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

<gadget id="calculator">22 * (1/2)</gadget>
<output>11</output>

<result>11</result>