Question

Can you explain the answer for me please and thank you

Answer 1

There's a formula for that.

... P(A∪B) = P(A) + P(B) - P(A∩B)

Filling in the given values, we have

... P(A∪B) = 2/3 + 4/5 - 3/5 = 10/15 + 12/15 - 9/15

... P(A∪B) = 13/15 . . . . . . . . matches selection B