The incubation period of duck is that of goose (14/15), the incubation period of chicken is that of goose (7/10), the incubation period of duck is 28 days, how many days is the incubation period of chicken?
鸭的孵化期是鹅的(14/15)，鸡的孵化期是鹅的(7/10)，鸭的孵化期为28天，鸡的孵化期是多少天？
<gadget id="calculator">14 / 15</gadget>
<output>14/15 = around 0.933333</output>

<gadget id="calculator">28 / (14/15)</gadget>
<output>30</output>

<gadget id="calculator">7 / 10</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">30 * (7/10)</gadget>
<output>21</output>

<result>21</result>