A law firm is maximizing shareholder value and wants to decide how much CSR to do. They decide that they want to do CSR in the form of pro-bono cases. The first three cases will cost the firm $3,000 each and each additional case after the third will cost the firm $6,000. Since they will take the most beneficial cases first, the first case will have benefits equal to $13,000, with each additional case benefiting the firm $3,000 less than the previous. How much total profit does the firm make from this CSR endeavor (hint: you first need to figure out how many cases they will take)?