The length of a rectangle with a perimeter of 18 cm is 6 cm, what is its width in cm
周长是18厘米的长方形的长是6厘米，它的宽是多少厘米
<gadget id="calculator">18 / 2</gadget>
<output>9</output>

<gadget id="calculator">9 - 6</gadget>
<output>3</output>

<result>3</result>