Task: Question Answering
Input (English): Problem: there are 18 balls in a jar . you take out 3 blue balls without putting them back inside , and now the probability of pulling out a blue ball is 1 / 5 . how many blue balls were there in the beginning ? 
Options: a ) 12 , b ) 9 , c ) 8 , d ) 7 , e ) 6
Output (English): e