Teacher Wang used a piece of iron wire to form a square with a side length of 6 cm. If this wire is used to surround a rectangle with a length of 9 cm, what is the width of the rectangle in cm?
王老师用一根铁丝刚好围成了一个边长是6cm的正方形，如果用这根铁丝围一个长是9cm的长方形，这个长方形的宽是多少cm？
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

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

<gadget id="calculator">12 - 9</gadget>
<output>3</output>

<result>3</result>