Andy has a collection of movie dvds. in andys collection 3/5 of the dvds are action 1/4 of the dvds are comedy. andy said that 4/9 of his collection is action or comedy. cynthia said that andy made an errer. explain wether andy is correct or incorect and why what fraction of the dvds in andys collection is not "action" or "comedy"

Andy is not correct because when adding the 2 fractions, he needs to create fractional parts with the same denominator.  NOTHING can be added unless the units are the same.  The denominator of a fraction are the units.  He needed to make 3/5 = 12/20 and 1/4 = 5/20.  Adding these together would be 17/20, making 3/20 of them NOT action or comedy.  17/20 + 3/20 = 20/20 or the total.