tulislah semua himpunan bagian dari{a,b,c,d}

{a,b,c,d} =
1 = {}
4 = {a}, {b}, {c}, {d}
6 = {a,b}, {a,c}, {a,d}, {b,c}, {b,d}, {c,d}
4 = {a,b,c}, {a,c,d}, {a,b,d}, {b,c,d}
1 = {a,b,c,d}

Semoga membantu... (^_^)