You are given P(X) = 0.23 P(X and Y) = 0.12 P(X or Y) = 0.34 = P(X) + P(Y) - P(X and Y) = 0.23 + P(Y) - 0.12. From the last equation, P(Y) = 0.34 - 0.23 + 0.12 = 0.23. Then the complement of P(Y) is P'(Y) = 1 - P(Y) = 1 - 0.23 = 0.77. ANSWER