A company sells umbrellas. Suppose that the number, 3:, of umbrellas that are sold per week is related to the price, p (in dollars), that is charged, according to the equation: p($) : 25 0.533 whereO g a: S 50 a) Find the marginal revenue when :1? : 20. [small V b) What does the quantity in part (a) represent? [59'9\"] "