The experience of a car dealer shows that 60% of the customers purchase a stereo as an option with their cars, 50% purchase tinted windows, and 35% purchase both. find the probability that a customer purchase at least one of these two options.

If 60% purchase a stereo and 50% purchases tinted windows, then the percentage of people who purchased both have been counted twice. So we have to subtract 35% (the % that purchased both) from the sum of the first two percentages:
60% + 50% - 35% = 75%
Therefore, the probability that a customer picked up any one or both options (which is at least 1) is 75%.