Let P(A) is the probability that a company executive will travel by plane and P(B) is the probability that he will travel by train.
Then,
P(A) = 2/5 and P(B) = 1/3
As he cannot be travel by plane and train at the same time, so P(A and B) = 0
Using formula, P(A or B) = P(A) + P(B) – P(A and B)
P(A or B) = 2/5 + 1/3 – 0
= 11/15
Therefore, probability of a company executive will be travelling by plane or train= P(A or B) = 11/15.