A reduction in the price of petrol by 10% enables a motorist to buy 5 gallons more for $280. Find the original price of petrol?
Choose the correct answer
A) $ 11  B) $ 5  C) $ 45  D) $ 400  E) $ 6.2

Rationale: price decreased by 10 % , so 9 / 10 times , which means that original gallons bought increased 10 / 9 times . since this increase equals to 5 gallons then 45 gallons were bought originally ( 45 * 10 / 9 = 50 - - > increase 5 gallons ) . hence original price was 280 / 45 = $ 6.2 answer : e .
Answer: E