Explanation
Given A = {x | x ∈ P ∧ 5 ≤ x ≤ 13}, where P is the set of prime numbers:
The prime numbers between 5 and 13 are 5, 7, 11, and 13.
So, A = {5, 7, 11, 13}, which has 4 elements.
The power set P(A) has 2^n elements, where n is the number of elements in A:
2^4 = 16