Over a one week period in the summer, the price of a gallon of gas increased from $2.35 to $2.82. By what percent did the price of gas increase over that week?

The price of gas increases from $2.35 to $2.82 or by $0.47 ($2.82 - $2.35 = $0.47).
The increase as a percentage of the original price is given by
($0.47/$2.35) x 100% = 20%

The answer is 20%
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