Task: Question Answering
Input (English): Problem: on a certain planet where people usually tend to live for more than a century , the ratio of present ages of father and son is 7 : 4 . 10 years later , the ratio of their ages will be 5 : 3 . what is the sum of their present ages ? 
Options: a ) 220 , b ) 200 , c ) 140 , d ) 80 , e ) 60
Output (English): a