Task: Question Answering
Input (English): Problem: joe invested a certain sum of money in a simple interest bond whose value grew to $ 260 at the end of 3 years and to $ 360 at the end of another 5 years . what was the rate of interest in which he invested his sum ? 
Options: a ) 6 % , b ) 8 % , c ) 10 % , d ) 12 % , e ) 15 %
Output (English): c