The power set P(B − A) is equal to 4, that is P(B−A) = {∅,{4},{5},{4,5}}.
To find the power set P(B − A), we first determine the elements of B - A.
The set B − A,which is the set of elements in B but not in A. In this case,
B − A = {4,5,6,8} - {2,6,7,8}
B − A = {4,5}.
The power set of a set is the set of all its subsets, including the empty set and the set itself. So, the power set of B − A is {∅,{4},{5},{4,5}}.
P(B − A) = 4
In conclusion, the power set P(B − A) have the four (4) elements {∅,{4},{5},{4,5}}, encompassing all possible subsets of the set resulting from the elements in B but not in A.