The perimeter of a rectangle is 36 cm, the width is 6 cm, and the length is in cm.
一个长方形的周长是36厘米，宽是6厘米，长是多少厘米．
<gadget id="calculator">36 / 2</gadget>
<output>18</output>

<gadget id="calculator">18 - 6</gadget>
<output>12</output>

<result>12</result>