if the naval research laboratory fired a chemist and the environmental protection agency hired her at the same salary, the net effect of these events would cause in aggregate demand.

Since both the U. S. Navy and the EPA are agencies of the federal government and therefore funded by taxes levied on the proletariat the salary remaining the same would balance one another out. No change. Therefore the effect on the aggregate demand would be null. Not considering the EPA tend to disseminate useful information more tha the military does. 
 

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