Would you be able to show all of the steps to finding the answer please? Thank you!

1:36 PM suppose the demand for a certain item is given by D(p) = - 5p - 8p + 400, where p represents the price of the item in dollars. a. Find the rate of change of demand with respect to price. b. Find and interpret the rate of change of demand when the price is $12. a. The rate of change of demand with respect to price is . (Simplify your answer.) b. Choose the correct answer below and fill in any answer boxes in your choice. O A. When the price is $12, demand is increasing at a rate of about increase in price of $1. items for each O B. When the price is $12, demand is decreasing at a rate of about each increase in price of $1. items for O C. When the price is $12, demand is increasing at a rate of about items for each increase in price of $12. O D. When the price is $12, demand is decreasing at a rate of about items for each increase in price of $12. 8. The graphing calculator window shows the graph of a function f(x) and its derivative function f'(x). Decide which is Y 1 the graph of the function and which is the graph of the derivative. Choose the graph that is the function and the graph that is the derivative. O Y2 is the graph of the derivative. Y, is the graph of the function. O Y1 is the graph of the derivative. Y2 is the graph of the function