I do not understand this question

A study nds that the noise from rock concerts is harmful; hence, the government imposes a $25 tax on the sale of every rock concert. This amount accurately accounts for the external cost of the noise pollution. Before the corrective tax, concert tickets regularly sold for $190. After the tax is in place, the market price for concert tickets rises to $205. Because of the tax, the number of concert tickets sold will v increase The socially optimal price of concert tickets is $ decrease The private market price is $ A rm selling concert tickets receives $ after it pays the tax