Task: Question Answering
Input (English): Problem: a person lent a certain sum of money at 5 % per annum at simple interest and in 8 years the interest amounted to $ 420 less than the sum lent . what was the sum lent ? 
Options: a ) 500 , b ) 600 , c ) 700 , d ) 800 , e ) 900
Output (English): c