Answer:

1.) Including all four elements, there are 24 = 16 subsets. 15 of those subsets are proper, 1 subset, namely {a,b,c,d}, is not. In general, if you have n elements in your set, then there are 2n subsets and 2n − 1 proper subsets.

2.) The list of all subsets of a,b,c,d is ϕ ,{a},{b},{c},{d},{a,b},{a,c},{a,d},{b,c},{b,d},{c,d},{a,b,c},{a,b,d},{a,c,d},{b,c,d},{a,b,c,d}

3.)

Step-by-step explanation:

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