A rectangular football field is 100 meters long and 45 meters wide. What is its circumference in meters?
一个长方形的足球场长100米，宽45米．它的周长是多少米？
<gadget id="calculator">100 + 45</gadget>
<output>145</output>

<gadget id="calculator">145 * 2</gadget>
<output>290</output>

<result>290</result>