A professional household raises 420 chickens, the number of ducks is equal to that of chickens (5/6), and the number of geese is equal to that of ducks (6/7). How many geese do you raise?
一个饲养专业户养鸡420只，养鸭的只数是鸡的(5/6)，鹅的只数是鸭的(6/7)．养鹅多少只？
<gadget id="calculator">5 / 6</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">6 / 7</gadget>
<output>6/7 = around 0.857143</output>

<gadget id="calculator">420 * (5/6) * (6/7)</gadget>
<output>300</output>

<result>300</result>