A 6-liter solution is 30% alcohol. How many liters of pure alcohol must be added to produce a solution that is 50% alcohol?  Options:
A) 1.8 B) 2.1 C) 2.4 D) 2.7 E) 3.0

Rationale: "let x be the amount of pure alcohol required . 0.3 ( 6 ) + x = 0.5 ( x + 6 ) 0.5 x = 3 - 1.8 x = 2.4 liters the answer is c ."
Answer: C