Task: Question Answering
Input (English): Problem: the average age of 25 students of a class is 25 years . out of these , the average age of 10 students is 22 years and that of the other 14 students is 28 years . the age of the 25 th student is ? 
Options: a ) 10 , b ) 15 , c ) 13 , d ) 11 , e ) 9
Output (English): c