Calculus Integration please help!!?

Marginal profit for the sale of widgets, in thousands of dollars, is P'(x) = 0.004x^2 + 0.3x + 3, and marginal cost, in thousands of dollars is C'(x) = 0.7x-4, where x is in thousands. Revenue is 5 when x=0. If 7,000 items are sold what is the price per item? Give your answer correct to two decimal places.