In a town, it was found that 40% families buy newspaper A, 20% families buy newspaper B, 10% families buy newspaper C, 5% families buy A and B, 3% buy B and C, 4% buy A and C and 40% buy none of A, B and C. If 200 families buy all the three newspapers, Find.
a) The number of families which buy newspaper A only.
b) The number of families which buy at least one of the three newspapers