People in town's demand for cigarettes is :P = 50 - Q/1500 , the marginal damage of consuming cigarettes is $7 per pack. The supply of cigarettes is...

People in town's demand for cigarettes is :P = 50 - Q/1500 , the marginal damage of consuming cigarettes is $7 per pack. The supply of cigarettes is perfectly elastic at $19.

Question: I need to find the economic incidence of the tax. Please also explain what is the economic incidence of the tax is.