A wire encloses a rectangle 10 cm long and 8 cm wide. If the wire is surrounded by a square, what is the side length of the square?
一根铁丝正好围成一个长10厘米，宽8厘米的长方形．如果把这根铁丝围成正方形，这个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>