If the price of gasoline increases by 25% and a driver intends to spend only 10% more on gasoline, by how much percent should the driver reduce the quantity of gasoline that he buys?  Options
A) 5 % B) 8 % C) 10 % D) 12 % E) 15 %

Rationale: "let x be the amount of gasoline the driver buys originally . let y be the new amount of gasoline the driver should buy . let p be the original price per liter . ( 1.25 * p ) y = 1.1 ( p * x ) y = ( 1.1 / 1.25 ) * x = 0.88 x which is a reduction of 12 % . the answer is d ."
Answer: D