A farm raised 4,000 chickens this year, an increase of 25% over last year. How many chickens were raised last year?
某饲养场今年养鸡4000只，比去年增加25%，去年养鸡多少只？
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 + (1/4)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">4_000 / (5/4)</gadget>
<output>3_200</output>

<result>3_200</result>