Task: Question Answering
Input (English): Problem: x and y are positive integers . when x is divided by 17 , the remainder is 3 , and when x is divided by 19 , the remainder is 1 . when y is divided by 14 , the remainder is 5 , and when y is divided by 21 , the remainder is 12 . what is the least possible value of y - x ? 
Options: a ) 15 , b ) 13 , c ) 11 , d ) 14 , e ) 18
Output (English): b