9. A survey of television viewers at A Child's Place Preschool produces the following data:
60% watch Sesame Street.
50% watch Captain Kangaroo.
50% watch Polka Dot Door.
30% watch Sesame Street and Captain Kangaroo.
20% watch Captain Kangaroo and Polka Dot Door.
30% watch Sesame Street and Polka Dot Door.
10% watch all three shows.
(a) What percentage view at least one of these programs?