P = {p:1 < p < 20}
Then, P = { 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19}
R = { r : 0 ≤ 25, r is a multiple of 4 }
Then R = { 0, 4, 8, 12, 16, 20, 24}
Thus, P ∩ R = {4, 8, 12, 16}