A 6-liter solution is 25% alcohol. How many liters of pure alcohol must be added to produce a solution that is 50% alcohol?	Select the correct option.
A) 2.1  B) 2.4  C) 2.7  D) 3.0  E) 3.3

Rationale: "let x be the amount of pure alcohol required . 0.25 ( 6 ) + x = 0.5 ( x + 6 ) 0.5 x = 3 - 1.5 x = 3 liters the answer is d ."
Answer: D