The perimeter of a rectangle is 26 meters, the length is 8 meters, and the width is in meters.
一个长方形的周长是26米，长是8米，宽是多少米．
<gadget id="calculator">26 / 2</gadget>
<output>13</output>

<gadget id="calculator">13 - 8</gadget>
<output>5</output>

<result>5</result>