Use a nylon rope to form a rectangle with a length of 6 decimeters and a width of 1.5 decimeters. If the nylon rope is changed into a square, what is the perimeter of the square in decimeters?
用一根尼龙丝绳围成一个长方形，长6分米，宽1.5分米，如果把这根尼龙丝绳改围成正方形，那么正方形的周长是多少分米．
<gadget id="calculator">6 + 1.5</gadget>
<output>7.5</output>

<gadget id="calculator">7.5 * 2</gadget>
<output>15</output>

<result>15</result>