Task: Question Answering
Input (English): Problem: a certain sum of money is divided among a , b and c such that a gets one - third of what b and c together get and b gets two - seventh of what a and c together get . if the amount received by a is $ 20 more than that received by b , find the total amount shared by a , b and c . 
Options: a ) $ 320 , b ) $ 420 , c ) $ 720 , d ) $ 220 , e ) $ 200
Output (English): c