There are 40 ducks in a pond.  50 percent of the ducks are Muscovy and 30 percent of the Muscovies are female.  How many female Muscovy ducks there?
Muscovies: 40(.50)=
<gadget id="calculator">40*.50</gadget>
<output>20</output>
20 Muscovy ducks.
Female Muscovies:20(.30)=6 ducks.

<result>6</result>