Theodore and Sarah have a small business selling custom-made T-shirts. They currently sell 250 shirts per month and charge $12 per T-shirt. Sarah thinks they can increase their revenue by increasing their selling price, but Theodore knows from experlence that each $l increase in price will decrease the number of T-shirts they sell by 7 shirts per month. Find an expression for the total monthly revenue Theodore and Sarah's business can generate if they change the selling price of their T-shirts. Let x represent the number of $1 increases in the price of the T-shirts.