The perimeter of a rectangle is 24 cm, the length is 8 cm, and the width is in cm.
一个长方形的周长是24厘米，长是8厘米，宽是多少厘米．
<gadget id="calculator">24 / 2</gadget>
<output>12</output>

<gadget id="calculator">12 - 8</gadget>
<output>4</output>

<result>4</result>