The width of a rectangle is 30 meters and the length is twice the width. What is the perimeter of the rectangle?
一个长方形的宽是30米，长是宽的2倍，这个长方形的周长是多少米
<gadget id="calculator">30 * 2</gadget>
<output>60</output>

<gadget id="calculator">60 + 30</gadget>
<output>90</output>

<gadget id="calculator">90 * 2</gadget>
<output>180</output>

<result>180</result>