A square vegetable field with one side against the wall, with a side length of 5 meters, surrounded by a fence, how many meters is the fence?
一块一面靠墙的正方形菜地，边长是5米，四周围上篱笆，篱笆长多少米？
<gadget id="calculator">5 * 4</gadget>
<output>20</output>

<result>20</result>