In a city 20 percent of the population travels by car, 50 percent travels by bus and 10 percent travels by both car and bus. Then persons travelling by car or bus is
60 percent
n(C) = 20, n(B) = 50, n(C ∩ B) = 10
Now n(C ∪ B) = n(C) + n(B) - n(C ∩ B)
= 20 + 50 - 10 = 60.