Task: Question Answering
Input (English): Problem: a solution of 70 litres contains oil and water in the ratio 9 : x . if 6 litres of water is added to the solution , the ratio becomes 6 : 4 , find the value of x ? 
Options: a ) 6 , b ) 8.5 , c ) 9 , d ) 6.5 , e ) 5
Output (English): e