A rectangular handkerchief has a circumference of 20 decimeters and a length of 6 decimeters. Do you know its width?
一块长方形手帕的周长是20分米，长是6分米，你知道它的宽是多少吗？
<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">10 - 6</gadget>
<output>4</output>

<result>4</result>