Help needed with Probability assignment, please see attached, thank you.

Problem 6. The managers of a car store observe that 70% of all the cars they sell are bought by pe0ple who already own a car. They also observe that 50% of the customers who come to the store but do not buy a car, already own one. Furthermore, 40% of the customers coming to the store buy a car. (a) What is the probability that a person coming to the shore already owns a car? (b) What is the probability that a car will be sold to a person who already has one? (c) What is more dicult for the managers: to sell a car to a person who already owns a car or to a person who does not own one