pls solve asap

Consider two firms with the following marginal abatement costs (MAC) as a function of emissions (E): MAC_1 = 18 - 2E_1 MAC_ 2 = 12 - E_2, and assume marginal external damages (MED) from the aggregate emissions of both firms (E_Agg = E_1 + E_2) is: MED = .5E_Agg To achieve the socially efficient level of aggregate emissions (E*_Agg), the government institutes a per-unit subsidy to abatement. The total for combined) subsidy payment to the two firms is $_