A case of 12 rolls of paper towels sells for $9. The cost of one roll sold individually is $1.What is the percent R of savings per roll for the 12-roll package over the cost of 12 rolls purchased individually?  Select the correct option: A) 9 % B) 11 % C) 15 % D) 25 % E) 90 %

Rationale: "cost of 12 paper towels individually = 1 * 12 = 12 cost of a set of 12 paper towels = 9 cost of one roll = 9 / 12 = 3 / 4 = 0.75 savings per roll = 1 - . 75 = 0.25 % of savings is r = . 25 / 1 * 100 = 25 % d is the answer ."
Answer: D