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The word GARDEN has 6 distinct letters. The vowels are A and E. If the vowels must be in alphabetical order (A before E), we can treat them as identical items when calculating permutations, and then arrange them in the required order. The number of permutations of n objects where p objects are identical is n! / p!. In this case, if A and E were treated as identical for arrangement purposes, the calculation would be 6! / 2! = 720 / 2 = 360. This is because for any arrangement of the 6 letters, only one of the two possible orderings of the vowels (AE or EA) will be alphabetical. Thus, the total arrangements where vowels are in alphabetical order is 6! / (number of permutations of vowels) = 6! / 2! = 360.