The width of a rectangular vegetable field is 4 meters, which is 1 meter less than the length. What is the perimeter of this vegetable field in meters?
一块长方形菜地的宽是4米，比长少1米，这块菜地的周长是多少米？
<gadget id="calculator">4 + 4 + 1</gadget>
<output>9</output>

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

<result>18</result>