A rectangular playground is 250 meters long and 200 meters wide. What is the perimeter of the playground?
一个长方形运动场，长250米，宽200米，这个运动场的周长是多少米？
<gadget id="calculator">250 + 200</gadget>
<output>450</output>

<gadget id="calculator">450 * 2</gadget>
<output>900</output>

<result>900</result>