A rectangle and a square have the same perimeter. The side length of the square is 9 cm. The length of the rectangle is 12 cm. What is the width of the rectangle in cm?
一个长方形和一个正方形的周长相等，正方形的边长是9厘米，长方形的长是12厘米，长方形的宽是多少厘米？
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

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

<gadget id="calculator">18 - 12</gadget>
<output>6</output>

<result>6</result>