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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
Solved.