Task: Question Answering
Input (English): Problem: mary invested a certain sum of money in a bank that paid simple interest . the amount grew to $ 260 at the end of 2 years . she waited for another 3 years and got a final amount of $ 350 . what was the principal amount that she invested at the beginning ? 
Options: a ) $ 220 , b ) $ 230 , c ) $ 240 , d ) $ 200 , e ) $ 250
Output (English): d