Task: Question Answering
Input (English): Problem: a began business with rs . 45000 and was joined afterwards by b with rs . 36000 . when did b join if the profits at the end of the year were divided in the ratio of 2 : 1 ? 
Options: a ) 1.5 , b ) 6 , c ) 7.5 , d ) 8.5 , e ) 2
Output (English): c