There are 1,580 ducks in the farm, which is 820 fewer than chickens. How many chickens are in the farm? (Resolution of equations containing unknown x)
饲养场养鸭1580只，比养的鸡少820只，饲养场养鸡多少只？(列含有未知数x的等式再解答)
<gadget id="calculator">1_580 + 820</gadget>
<output>2_400</output>

<result>2_400</result>