The perimeter of the rectangle is 48 cm, the length is 18 cm, and what is the width.
长方形的周长是48厘米，长是18厘米，宽是多少．
<gadget id="calculator">48 / 2</gadget>
<output>24</output>

<gadget id="calculator">24 - 18</gadget>
<output>6</output>

<result>6</result>