e: st Wor arrent tempt The demand, D, for a new rollerball pen is given by D = 0.009p3-0.8p2+170p, where p is the price in dollars. a) Find the rate of change of quantity with respect to price, dD/dp. b)How many units will consumers want to buy when the price is $25 per unit? c)Find the rate of change at p 25, and interpret this result. d)Would you expect dD/dp to be positive or negative? Quest dD a) Quest dp