Task: Question Answering
Input (English): Problem: the ratio of boarders to day students at a school was originally 2 to 5 . however , after a number of new boarders join the initial 60 boarders , the ratio changed to 1 to 2 . if no boarders became day students and vice versa , and no students left the school , how many new boarders joined the school ? 
Options: a ) 12 , b ) 15 , c ) 20 , d ) 24 , e ) 30
Output (English): b