Those who suffer from allergies can take medicine to relieve their suffering. Without treatment, they will have 118 bad days per year. Generic drug G costs $76 for an annual prescription, whereas brand name drug B costs $680. With drug G, most people suffer only 42 days of allergy symptoms, whereas drug B seems a bit better, usually reducing symptomatic days to just 38. 

What is the average cost per day of symptom relief with drug G? With drug B? 

What is the marginal cost per additional day of relief if a patient is switched from drug G to drug B?