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Market Research suggests that for a given commodity Q= 2 when P= 60, Q = 3 when P= 90 and Q=5 when P= 100, where Q stands for quantity and P stands for price. a) Find the firm's demand function where P = f(Q) (assume it is quadratic). (13 marks) b) Find intercepts, a maximum or minimum point of the following function: II =-30 +70Q -3Q2 (12 marks) c) Draw a graph of the function in part b, i.e.: II = -30 +70Q -3Q- (8.3 marks)