A rectangular farmland is 27 meters long and 9 meters wide. Uncle Wang dug a ditch along the perimeter of the farmland. How long is the ditch?
一块长方形农田，长27米，宽9米，王大伯沿着农田的四周挖了一条水沟，水沟长多少米？
<gadget id="calculator">27 + 9</gadget>
<output>36</output>

<gadget id="calculator">36 * 2</gadget>
<output>72</output>

<result>72</result>