The chicken farm raised 3,600 chickens this year, an increase of 80% over last year. How many chickens were raised last year?
养鸡场今年养鸡3600只，比去年增加80%，去年养鸡多少只？
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 + (4/5)</gadget>
<output>9/5 = around 1.8</output>

<gadget id="calculator">3_600 / (9/5)</gadget>
<output>2_000</output>

<result>2_000</result>