Task: Question Answering
Input (English): Problem: if x is invested in a bank at a rate of simple interest of y % p . a . for two years , then the interest earned is 500 . if x is invested at y % p . a . , for two years when the interest is compounded annually , the interest is 512.50 . what is the value of x ? 
Options: a ) 8000 , b ) 6000 , c ) 5000 , d ) 4000 , e ) 3000
Output (English): c