The gym offers a discount when more than one member of the family joins. The first member (n=0) pays $550 per year. The second member to join (n=1) gets a discount of $75 per year. The third member (n=2) gets an additional $75 discount. The price for the nth member is given by 550+(-75n).

a. What is the price for the fourth member to join (n=3)?

b. For a large family, is it possible that member would join for free? If so, which member would it be? Explain your reasoning.

c. Other than $0, what is the lowest amount that a member would pay to join? Which member would it be? Explain your reasoning.