Cully furniture buys two products for resale: big shelves (b) and medium shelves (m). each big shelf costs $500 and requires 100 cubic feet of storage space, and each medium shelf costs $300 and requires 90 cubic feet of storage space. the company has $75,000 to invest in shelves this week, and the warehouse has 18,000 cubic feet available for storage. profit for each big shelf is $300 and for each medium shelf is $150. what is the maximum profit?