A rectangular vegetable field is 5 meters long and 3 meters wide. There is a fence around the vegetable field. How long is the fence?
一块长方形菜地，长5米，宽3米，在菜地四周围一圈栅栏，栅栏长多少米？
<gadget id="calculator">5 + 3</gadget>
<output>8</output>

<gadget id="calculator">8 * 2</gadget>
<output>16</output>

<result>16</result>