The relationship between the amount of money x that a small instrument manufacturer spends on advertising and the total sale is given by the function S(x) = -0.003x + 0.58x-200. Find the average rate of change expected in the sales when the amount spend on advertising increases from $50 to $100. a. 17.9 b. 34.5 c. 27.2 d. 44.1 e. None of the above