A square lawn has a perimeter of 20 meters. What is the perimeter of two such lawns connected together?
一个正方形草坪，周长是20米，两块这样的草坪连在一起周长是多少米？
<gadget id="calculator">20 / 4</gadget>
<output>5</output>

<gadget id="calculator">8 - 2</gadget>
<output>6</output>

<gadget id="calculator">5 * 6</gadget>
<output>30</output>

<result>30</result>