Eric purchased three music cds and a sweatshirt from a band's online store and received a 20% discount. he paid $100 for his purchase. the following week, the same store offered a 40% discount on all its products. eric's friend neil took advantage of the sale and bought four music cds and two sweatshirts for $120. assuming that the actual prices of the music cds and the sweatshirts are unchanged, the price of a music cd is $

a. 20.
b. 25.
c. 30.
d. 50.

and the price of a sweatshirt is $

a. 20.
b. 25.
c. 30.
d. 50.