The total number of people in a recent poll is 3000.
\The number of people in white sox team is
of the total number of people.
So the number of people in white sox team
.
The number of people in red sox team is
of the total number of people.
So the number of people in red sox team
.
The number of people in cubs team = total number of peoples
(white sox team + red sox).
The number of people in cubs team 

.
The number of people in cubs team is 500.