After a storm deposits 120 billion gallons of water into the city reservoir, the reservoir is 80% full. If the original contents of the reservoir totaled 200 billion gallons, the reservoir was approximately what percentage full before the storm?  Choose the correct choice from the following options.
A) 45%
B) 48%
C) 50%
D) 58%
E) 65%
When the storm deposited 120 billion gallons, volume of water in the reservoir = 200 + 120= 
<gadget id="calculator">200 + 120</gadget>
<output>320</output>
320 billion gallons   If this is only 80% of the capacity of the reservoir, the total capacity of the reservoir= 320/0.8= 
<gadget id="calculator">320/0.8</gadget>
<output>400</output>
400 billion gallons   Therefore percentage of reservoir that was full before the storm= (200/400)*100= 
<gadget id="calculator">(200/400)*100</gadget>
<output>50</output>
50%   Option 50%
<result>C</result>
After a storm deposits 120 billion gallons of water into the city reservoir, the reservoir is 80% full. If the original contents of the reservoir totaled 200 billion gallons, the reservoir was approximately what percentage full before the storm?