Two firms can control emissions at the following marginal costs: MC1=$200q1, MC2=$100q2, where q1 and q2 are, respectively, the amount of emissions reduced by the first and second firms. Assume that with no control at all, each firm would be emitting 20 units of emissions or a total of 40 units for both firms.

1. Compute the cost-minimizing allocation of control responsibility if a total reduction of 21 units of emission is necessary. (10 marks)
2. Compute the optimal emission charge/tax per unit of emission that results in cost-minimizing allocation in part 'a'. (5 marks)