Given the 5 letters a,b,c,d, and e, determine how many different 3 letter arrangements can be formed, if the order of the letters is disregarded.
What does it mean when the order of the letters is disregarded?
If the order is disregarded, then it doesn't matter (I'm guessing that's what they mean),
so (a,b,c) is the same as (b,a,c) and (c,b,a) etc.
Whereas if the order were taken into account, then (a,b,c), (b,a,c), (c,b,a) would all be distinct arrangements.