There are 280 chickens in the farm, which is 2/5 more than ducks. How many ducks are raised in the farm?
饲养场养鸡280只，比鸭多(2/5)，饲养场养鸭多少只？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 + (2/5)</gadget>
<output>7/5 = around 1.4</output>

<gadget id="calculator">280 / (7/5)</gadget>
<output>200</output>

<result>200</result>