After a storm deposits 120 billion gallons of water into the city reservoir, the reservoir is 50% full. If the original contents of the reservoir totaled 280 billion gallons, the reservoir was approximately what percentage full before the storm? Choose the correct choice from the following choices:
A) 45% B) 48% C) 54% D) 58% E) 65%
When the storm deposited 115 billion gallons, volume of water in the reservoir = 280 + 120= 
<gadget id="calculator">280 + 120</gadget>
<output>400</output>
400 billion gallons   If this is only 80% of the capacity of the reservoir, the total capacity of the reservoir= 400/0.5= 
<gadget id="calculator">400/0.5</gadget>
<output>800</output>
800 billion gallons   Therefore percentage of reservoir that was full before the storm= (280/800)*100= 
<gadget id="calculator">(280/800)*100</gadget>
<output>35</output>
35%   Option 54%
<result>C</result>
After a storm deposits 120 billion gallons of water into the city reservoir, the reservoir is 50% full. If the original contents of the reservoir totaled 280 billion gallons, the reservoir was approximately what percentage full before the storm?