There are 409 ducks in the farm, which is 9 more than 20% of chickens. How many chickens are there in the farm?
饲养场里有鸭409只，比鸡的20%多9只，饲养场里养鸡多少只．
<gadget id="calculator">409 - 9</gadget>
<output>400</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">400 / (1/5)</gadget>
<output>2_000</output>

<result>2_000</result>