After a storm deposits 115 billion gallons of water into the city reservoir, the reservoir is 80% full. If the original contents of the reservoir totaled 245 billion gallons, the reservoir was approximately what percentage full before the storm?	Pick.
A) 45 % B) 48 % C) 54 % D) 58 % E) 65 %

Rationale: "when the storm deposited 115 billion gallons , volume of water in the reservoir = 245 + 115 = 360 billion gallons if this is only 80 % of the capacity of the reservoir , the total capacity of the reservoir = 360 / 0.8 = 450 billion gallons therefore percentage of reservoir that was full before the storm = ( 245 / 450 ) * 100 = 54.4 % option c"
Answer: C