Answer:
The rate of evaporation in gallons per year will be 
 gallons per year.
Explanation:
The amount of annual evaporation from the Hoovers dam is approximately 
 acre-feet.
Now, 1 acre-foot of water is equivalent to 326000 gallons of water.
So, the total volume of water that evaporates per year from the dam will be 
.
Therefore, the rate of evaporation in gallons per year will be 
 gallons per year. (Answer)