mixture contains alcohol and water in the ratio 4 : 3. If 6 liters of water is added to the mixture, the ratio becomes 4: 5. Find the quantity of alcohol in the given mixture.  Choose the correct choice from the following answers:
A) 10 B) 6.8 C) 27 D) 22 E) 29

Rationale: "let the quantity of alcohol and water be 4 x litres and 3 x litres respectively 24 x = 4 ( 3 x + 5 ) 12 x = 20 x = 1.7 quantity of alcohol = ( 4 x 1.7 ) litres = 6.8 litres . answer : b"
Answer: B