colored ribbon exactly forms a square with a side length of 6 cm. If it is now changed to a rectangle with a width of 4 cm, what is the length of the rectangle surrounded by this colored ribbon in cm?
一根彩色丝带正好围成一个边长为6厘米的正方形．如果现在改围成宽为4厘米的长方形，那么这个彩色丝带围成的长方形的长是多少厘米．
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">6 * 2</gadget>
<output>12</output>

<gadget id="calculator">12 - 4</gadget>
<output>8</output>

<result>8</result>