The perimeter of the rectangle is 24cm, the width is 4cm, what is the length in cm
长方形的周长是24cm，宽是4cm，长是多少cm
<gadget id="calculator">24 / 2</gadget>
<output>12</output>

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

<result>8</result>