What are the names of all colleges with students who tried out for the position of goalie?
select cname from tryout where ppos = "goalie"
What is the number of people enrolled in all the other colleges?
select cname, enr from college where cname not in (select cname from tryout where ppos = "goalie")
How many is that in total?
select sum(enr) from college where cname not in (select cname from tryout where ppos = "goalie")