How ma y downloaded songs, d, must be purchased for the monthly price of Napster to be the same as iTunes?

Question

The cost to purchase a song from iTunes is $0.99 per song. To purchase from Napster, you must be a member. The Napster membership fee is $10. I'm addiyion, each purchased song costs $0.89. How many downloaded songs, d, must be purchased for the monthly price of Napster to be the same as iTunes?

Answer 1

0.99d = 0.89d + 10

0.1d = 10

d = 100