Task: Question Answering
Input (English): Problem: a fold density is 19 times greater than the water and for copper it is 9 times . at what ratio you can mix gold and copper to get 15 times denser than water . ? 
Options: a ) 3 : 1 , b ) 3 : 2 , c ) 3 : 5 , d ) 3 : 8 , e ) 3 : 7
Output (English): b