“In considering producer-to-consumer externalities, it is stated that where there are multiple sources of emissions, and where only individuals suffer from pollution, each source should be taxed at the same rate. Use the Lagrangian for the efficiency to prove this, and derive the tax rate.”

用拉格朗日函数证明征税的效率和税率。哪位高手能证明一下啊！！跪谢了！！