The perimeter of a rectangle is 10 meters, the length is 3 meters, and the width is in meters.
一个长方形的周长是10米，长是3米，宽是多少米．
<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">5 - 3</gadget>
<output>2</output>

<result>2</result>