A survey of auto consumers shows the buying preferences of consumers in Asia. Out of 120 cars included in the survey, 75 are brand new and the rest are used cars. Of the new cars, 12 are MAZDAs, 25 BMWs, 27 KIAs, and rest is Citroens. Of the used cars, 14 are MAZDAs, 13 are BMWs, and the rest of them are Citroens. Based on this data, calculate the following.

a. The probability that a buyer purchases a used car.
b. The probability that a buyer purchases a Citroen.
c. The probability that a buyer does not purchase BMW.
d. The probability that a buyer purchases a used car that is a MAZDA.