Task: Question Answering
Input (English): Problem: in a mixture 60 litres , the ratio of milk and water 2 : 1 . if this ratio is to be 1 : 2 , then the quanity of water to be further added is : 
Options: a ) 20 , b ) 30 , c ) 40 , d ) 50 , e ) 60
Output (English): e