There were 700 chickens in the chicken farm, 300 were sold, and 500 chicks were hatched. How many chickens are there now?
养鸡场原来有700只鸡，卖了300只，又孵出500只小鸡．现在有多少只鸡？
<gadget id="calculator">700 - 300</gadget>
<output>400</output>

<gadget id="calculator">400 + 500</gadget>
<output>900</output>

<result>900</result>