There are 4,500 chickens in a farm, and the ratio of the number of chickens to the number of ducks is 5:4. How many ducks are raised in this farm?
某饲养场养鸡4500只，养鸡的只数和养鸭的只数比是5：4，这个饲养场养鸭多少只？
<gadget id="calculator">4_500 / 5</gadget>
<output>900</output>

<gadget id="calculator">900 * 4</gadget>
<output>3_600</output>

<result>3_600</result>