arithmetic - there are 4 books on fairy tales 5 novels and 3 plays in how many ways can you arrange these so that books on fairy tales are together novels are together and plays are together and in the order books on fairy tales novels and - skillgun

There are 4 books on fairy tales and they have to be put together.
They can be arranged in 4! ways.
Similarly, there are 5 novels.
They can be arranged in 5! ways.
And there are 3 plays.
They can be arranged in 3! ways.
So, by the counting principle all of them together can be arranged in 4!*5!*3!= 17280 ways