Compact Disc Collection Gitti is a fan of the music of Paul Simon and Art Garfunkel.In her collection of 25 compact disc, she has the following:
5 on which both Simon and Garfunkel sing
7 on whixh Simon sings
8 on which Garfunkel sings
15 on which neither Simon nor Garfunkel sings.
a) How many of her compact disc feature only Paul Simon?
b) How many of her compact discs feauture only Art Garfunkel?
c) How many feauture at least one of these two artists?
d) How many feature at most one of these two artists.