The following data were observed at Demirköprü Dam site on Gediz River in June 1971. Find the monthly evaporation in (mathrmmm) from the reservoir surface of this dam. If there were no inflows or outflows during this month, and the initial storage of the reservoir was 5000 million cubic meters, and the final storage was 4800 million cubic meters, What is the monthly evaporation in (mathrmmm)?