rectangle with a length of 10 cm and a width of 8 cm is surrounded by a wire. If this wire is used to surround a square, what is the side length of the square in cm?
用一根铁丝围成了一个长10厘米，宽8厘米的长方形，如果用这根铁丝去围一个正方形，那么正方形的边长是多少厘米？
<gadget id="calculator">10 + 8</gadget>
<output>18</output>

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

<gadget id="calculator">18 * (1/2)</gadget>
<output>9</output>

<result>9</result>