Task: Question Answering
Input (English): Problem: if 4 x + y + z = 80 , 2 x - y - z = 4003 x + y - z = 20 for integers of x , y and z , find x = ? 
Options: a ) 10 , b ) 20 , c ) 15 , d ) 26 , e ) 18
Output (English): b