Martha opens a new cell phone store. She spends $24,500 purchasing inventory to sell, buying furniture, and advertising her business. The table below shows how Martha calculates various costs and profits in her business.

I'm at a bookstore with $\$35$ in my pocket and a $20\%$-off coupon. what is the cost of the most expensive book i can buy with my money and the coupon? (assume that there are books of every possible price in the bookstore. it's a large bookstore! )