From a survey conducted with the employees of an institution, it was noticed that 45% of the employees own a house in Tirana. Among the employees who own houses in Tirana, 25% of them own a house on the coast. From the survey, it was noticed that 60% of the employees do not own a house on the coast. An employee from this institution is randomly selected. Calculate the probability that: a) The employee owns a house in Tirana and a beach. b) The employee does not own a house either in Tirana or on the coast. c) The employee owns a house in Tirana and does not own a house on the coast d) The employee owns a house in Tirana when it is known that he does not own a house on the coast.