A gym is thinking about adding more cardio equipment for its members. It is considering two types of equipment, treadmills (T) and Stair Masters (S). The gym surveyed a sample of the members and asked which equipment they used in the previous month. Of 150 gym members surveyed it was found that… 102 used the treadmills 71 used the Stair Masters 40 used both types. a) How many did not use either the treadmill or the Stair Master? b) How many used the treadmill but not the Stair Master? c) How many used the Stair Master but not the treadmill? d) How many used at least one of the two?