95. Price-demand equation. According to economic theory, the demand x for a quantity in a free market decreases as the price p increases (see the figure). Suppose that the number x of DVD players people are willing to buy per week from a retail chain at a price of $p is given by x = 4,000 / (0.1p + 1), 10 <= p <= 70. (A) Find dx/dp. (B) Find the demand and the instantaneous rate of change of demand with respect to price when the price is $40. Write a brief interpretation of these results. (C) Use the results from part (B) to estimate the demand if the price is increased to $41.