There are 250 ducks in the farm, and twice as many chickens as ducks. How many chickens and ducks are there in the farm?
饲养场养鸭250只，养鸡的只数是鸭的2倍．饲养场养鸡和鸭共有多少只？
<gadget id="calculator">250 * 2</gadget>
<output>500</output>

<gadget id="calculator">500 + 250</gadget>
<output>750</output>

<result>750</result>