What is the width of a rectangle with a perimeter of 56 meters and a length of 10 meters?
周长是56米的长方形，长10米，宽是多少．
<gadget id="calculator">56 / 2</gadget>
<output>28</output>

<gadget id="calculator">28 - 10</gadget>
<output>18</output>

<result>18</result>