A firm offers terms of 2/15, net 60. a. What effective annual interest rate does the firm earn when a customer does not take the discount? (Do not round intermediate calculations and enter your answer as a percent rounded to 2 decimal places, e.g., 32.16.) Effective annual interest rate % b. What effective annual interest rate does the firm earn if the discount is changed to 3 percent? (Do not round intermediate calculations and enter your answer as a percent rounded to 2 decimal places, e.g., 32.16.) Effective annual interest rate % c. What effective annual interest rate does the firm earn if the credit period is increased to 80 days? (Do not round intermediate calculations and enter your answer as a percent rounded to 2 decimal places, e.g., 32.16.) Effective annual interest rate % d. What effective annual interest rate does the firm earn if the discount period is increased to 20 days? (Do not round intermediate calculations and enter your answer as a percent rounded to 2 decimal places, e.g., 32.16.) Effective annual interest rate %