If the price in dollars of a stereo system is given by p(q) = 7600/q^2 + 1000, where q represents the demand for the product, find the marginal revenue when the demand is 20. What is the formula for the revenue function? A. R(q) = pq B. R(q) = p/q C. R(q) = p'p D. R(q) = p'q The marginal revenue for the given demand is $ .