3. Find the marginals (slopes) of the following functions: TB = 170x - x2 TC = 100 - 10x2 TB = 100 x - 2x2 TC = 80+ 52x - 6x3+ Vix3 TB = 8.A - 0.004A- TC = A + 0.00642 4. If total benefit is given as TB = 170x -x and total cost is given as TC = 100 - 10x-, determine the level of the activity that maximizes net benefit (NB). What is the maximum net benefit (NB)? 5. If total benefit is given as TB = 8A - 0.004A- and total cost is given as TC = A + 0.00642 determine the level of the activity that maximizes net benefit (NB). What is the maximum net benefit (NB)