A company is having business cards printed. The cost to design the business card is $20. There is an additional cost of $0.05 per business card printed.

a. Identify the fixed cost and the variable cost in this relationship.
b. Is this an example of partial or direct variation? Justify your reasoning.
c. Write an equation representing this relationship. Don't forget to define your variables.
d. Use your equation to determine the total cost of 600 business cards.