There are 4000 ducks in the poultry farm, which is 400 less than the number of chickens (2/5). How many chickens are there on the farm?
家禽养殖场养了鸭4000只，比鸡只数的(2/5)少400只．养殖场养了多少只鸡？
<gadget id="calculator">4_000 + 400</gadget>
<output>4_400</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">4_400 / (2/5)</gadget>
<output>11_000</output>

<result>11_000</result>