[[0, 5, 10], [1, 6, 11], [2, 7, 12], [3, 8, 13], [4, 9, 14], [5, 10, 0], [6, 11, 1], [7, 12, 2], [8, 13, 3], [9, 14, 4], [10, 0, 5], [11, 1, 6], [12, 2, 7], [13, 3, 8], [14, 4, 9]]
Since Z mod n is abelian, H is a normal subgroup.
The 0 + H coset is:
[0, 5, 10].
The 1 + H coset is:
[1, 6, 11].
The 2 + H coset is:
[2, 7, 12].
The 3 + H coset is:
[3, 8, 13].
The 4 + H coset is:
[4, 9, 14].
Since Z mod n is abelian, H is a normal subgroup.
The 0 + H coset is:
[0, 7, 14].
The 1 + H coset is:
[1, 8, 15].
The 2 + H coset is:
[2, 9, 16].
The 3 + H coset is:
[3, 10, 17].
The 4 + H coset is:
[4, 11, 18].
The 5 + H coset is:
[5, 12, 19].
The 6 + H coset is:
[6, 13, 20].
Since Z mod n is abelian, H is a normal subgroup.
The 0 + H coset is:
[0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95].
The 1 + H coset is:
[1, 6, 11, 16, 21, 26, 31, 36, 41, 46, 51, 56, 61, 66, 71, 76, 81, 86, 91, 96].
The 2 + H coset is:
[2, 7, 12, 17, 22, 27, 32, 37, 42, 47, 52, 57, 62, 67, 72, 77, 82, 87, 92, 97].
The 3 + H coset is:
[3, 8, 13, 18, 23, 28, 33, 38, 43, 48, 53, 58, 63, 68, 73, 78, 83, 88, 93, 98].
The 4 + H coset is:
[4, 9, 14, 19, 24, 29, 34, 39, 44, 49, 54, 59, 64, 69, 74, 79, 84, 89, 94, 99].
The 5 + H coset is:
[5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 0].
The 6 + H coset is:
[6, 11, 16, 21, 26, 31, 36, 41, 46, 51, 56, 61, 66, 71, 76, 81, 86, 91, 96, 1].