(1) If the total cost of a firm is C(x) =1.5x' -5x +20x+5. Find the marginal cost (in dollars) when 25 units are produced and sold. 2 (2) The number q of roller blades a firm is willing to sell per week at a price of $p is given by q=60,/p+25+300 for 20s p $ 100. (i) Find dq dp (ii) Find the amount supplied when the price is $56. (ii) Find the instantaneous rate of change of supply with respect to price when the price is $56