The perimeter of a rectangle is 48 cm, its length is 15 cm, and its width is in cm.
一个长方形的周长是48厘米，它的长是15厘米，宽是多少厘米．
<gadget id="calculator">48 / 2</gadget>
<output>24</output>

<gadget id="calculator">24 - 15</gadget>
<output>9</output>

<result>9</result>