The quality of water that should be added to reduce 9 ml. Lotion containing 50 % alcohol to a lotion containing 30 % alcohol is_________?

A. 3 ml
B. 4 ml
C. 5 ml
D. 6 ml
Explanation:
Alcohol in 9 ml lotion = (50/100 × 9)ml = 4.5ml
Water in it = (9 – 4.5)ml = 4.5ml
Let x ml of water be added to it, then 4.5/9+x × 100 = 30
=> 4.5/9+x = 30/100 = 3/10
=> 3(9+x) = 45 => 27 + 3x = 45
=> 3x = 18
=> x = 6
Water to be added = 6 ml