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QUESTION 6 The monthly sales of Sunny Electronics' new sound system are given by q(t) = 6,000t - 6012 units per month, t months after its introduction. The price Sunny charges is p(t) = 3,000 - t dollars per sound system, t months after introduction (a) Find the rate of change of monthly sales. (b) Find the rate of change of price. (c) Find the rate of change of monthly revenue 5 months after the introduction of the sound system. $ per month QUESTION 7 Find the marginal cost, that is, find the derivative using the limit definition