What is the average value of points?
select avg(points) from player
How many players have points less than 20.0?
select count(*) from player where points < 20
What are the positions of those players?
select position from player where points < 20
What about the positions of those players who have more than 20 points and less than 10 points.
select position from player where points > 20 intersect select position from player where points < 10