The price of labour is $20 per unit and the price of capital is $50 per unit. To produce 40 units of output the firm needs to hire units of labour. The 60th unit of output adds $ to long-run total cost. The Long Run Average Cost of producing 100 units of output is $ The Long Run Total Cost of producing 120 units of output is $ To produce 140 units of output the firm needs to hire units of capital..