Two professional chicken farmers, A and B, raise a total of 3,000 chickens. After professional chicken farmer B sells 800 chickens, the number of chickens in professional chicken farmer A is exactly three times the number of chickens left by professional chicken farmer B. How many chickens did A raise? Use equations and formulas in two ways.
甲乙两个养鸡专业户一共养鸡3000只．乙养鸡专业户卖掉800只鸡后，甲养鸡专业户鸡的只数正好是乙养鸡专业户剩下只数的3倍．甲原来养多少鸡？用方程和算式两种方法．
<gadget id="calculator">3_000 - 800</gadget>
<output>2_200</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 + (1/3)</gadget>
<output>4/3 = around 1.333333</output>

<gadget id="calculator">2_200 / (4/3)</gadget>
<output>1_650</output>

<result>1_650</result>