Southwest U's campus book store sells course packs for $15 each. The variable cost per pack is $10, and at current annual sales of 63,000 packs, the store earns $75,000 before taxes on course packs. How much are the fixed costs of producing the course packs?

a. $390,000

b. $240,000

c. $870,000

d. $555,000

e. $315,000