The marginal cost function associated with producing & widgets is given by C' (x) = -0.4x + 50 where C' (I) is measured in dollars/unit and I denotes the number of widgets. If the daily fixed costs incurred in the production is $800, find the total cost C() incurred in producing the first 100 units of the day. O $3,400 O $3,800 O $4,200 O $4,300 O $4,000