How many different ways can seven students be seated in a row of seven seats if there must be exactly two people between Alex and Betsy, and exactly two people between Betsy and Cass?
Anchor Betsy in any seat
Then there are two ways to seat Alex and Cass
And the number of ways to seat the other4 people = 4! = 24
So.....the toal arrangements = 2 * 24 = 48