Mrs. Bell's class is selling Hobbs Middle Jaguar t-shirts to raise money for a trip. They typically sell 400 t-shirts a year for $10 per shirt. Mrs bell knows that for every $1 increase in price, they will sell 20 less t-shirts. What is the revenue function R (x), where x represents the $1 price increases and revenue is equal the number of t-shirts sold times the cost of each shirt

Given that for every $1 increase in the price of the t-shirts, they will sell 20 less shirts. The revenue function R (x) is giiven by R (x) = (400 - 20x) (10 + x) = 4000 + 200x - 20x^2. Therefore, the revenue function representing the revenue Mrs Bell's class earns from selling Hobbs Middle Jaquar t-shirts is given by R (x) = 4000 + 200x - 20x^2 where x represent the $1 price increases and revenue is equal to the number of t-shirts sold times the cost of each shirt.