If the length of a rectangle is 5 cm and the width is 1 cm shorter than the length, what is the perimeter of the rectangle in cm?
一个长方形长5厘米，宽比长短1厘米，长方形的周长是多少厘米．
<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>