How can I graph a scenario indicating the the socially efficient quantity of a unit, the total amount of the unit, where there is a marginal willingness to pay equal to 800 - 4Q (Q is in units per day) and the private marginal costs of this unit are represented by MCp = 2Q, and the social marginal costs per visit are equivalent to the private marginal costs up to Q=100, but for Q100, MCs = 200+4(Q-100), as well as calculate the Pigouvian per-unit tax?