If the length of a rectangle is 5 meters and its width is 1 meter, what is its perimeter in meters?
长方形的长是5米，比宽长1米，它的周长是多少米．
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">5 + 4</gadget>
<output>9</output>

<gadget id="calculator">9 * 2</gadget>
<output>18</output>

<result>18</result>