The length of a rectangular vegetable field is 30 meters and the length is three times the width. What is the circumference of this vegetable field in meters?
一块长方形菜地的长是30米，长是宽的3倍．这块菜地的周长是多少米？
<gadget id="calculator">30 / 3</gadget>
<output>10</output>

<gadget id="calculator">30 + 10</gadget>
<output>40</output>

<gadget id="calculator">40 * 2</gadget>
<output>80</output>

<result>80</result>