→ (Given)

= 1 – P(A⋃B) → (1)

= 1 – [P(A) – P (A⋂B)] → (2)

Now,

P(A⋂B) = P(B) 1/2

P(A⋂B)

→ (3)

According to the addition theorem of probability,

P(A⋃B) = P(A) + P(B) – P(A⋂B)

→ From (3) and (Given)

→ (4)

Now using Equation (1) and (2)

P (A⋃B) + P() = 1 – P(A⋃B) + 1 – [P(A) – P (A⋂B)]