Task: Question Answering
Input (English): Problem: a money lender lent rs . 800 at 3 % per year and rs . 1400 at 5 % per year . the amount should be returned to him when the total interest comes to rs . 350 . find the number of years . 
Options: a ) 3.5 , b ) 3.72 , c ) 4 , d ) 4.25 , e ) 4.5
Output (English): b