hmm, there are 5 letters
if you cannot repeat the letters
hmm, let's find how many for 4 letters
there are 4! or 4*3*2*1=24
that's how many ways there are to arrange a,b,c, d
now we can multiply it by 4 because there are 4 choices for the last place (e is not included0
24*4=56
answer is 56 different arrangements