What is the largest submission score?
select max(scores) from submission
How many submissions have a score larger than 90?
select count(*) from submission where scores > 90
How about the number of submissions with a score less than 80?
select count(*) from submission where scores < 80
What are the colleges that have both authors with submission score larger than 90 and authors with submission score smaller than 80?
select college from submission where scores > 90 intersect select college from submission where scores < 80