UPSC NDA Math Model Paper 9

Given: U = {x : x is the natural number less than 20}.
A = {0, 2, 7, 15, 19, 20} and B = {5, 7, 9, 11, 13, 17, 20}
U = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19}
A = {0, 2, 7, 15, 19, 20}
B = {5, 7, 9, 11, 13, 17, 20}
(A - B) = {0, 2, 15, 19}
(A - B) ∩ U = {2, 15, 19}
It is very clearly visible (A - B) ∩ U is a subset of U and A