Xiao Ming's family has 8 chickens and 45 symbiotic eggs. Each hen lays 9 eggs. How many roosters are there in these chickens?
小明家养了8只鸡，共生蛋45只，每只母鸡生9个蛋，这些鸡中有几只公鸡？
<gadget id="calculator">45 / 9</gadget>
<output>5</output>

<gadget id="calculator">8 - 5</gadget>
<output>3</output>

<result>3</result>