Task: Question Answering
Input (English): Problem: a sum of money lent out at s . i . amounts to a total of $ 520 after 2 years and to $ 820 after a further period of 5 years . what was the initial sum of money that was invested ? 
Options: a ) $ 340 , b ) $ 360 , c ) $ 380 , d ) $ 400 , e ) $ 420
Output (English): d