Task: Question Answering
Input (English): Problem: if 4 xz + yw = 6 and xw + yz = 12 , what is the value of the expression ( 2 x + y ) ( 2 z + w ) ? 
Options: a ) 9 . , b ) 30 . , c ) 15 . , d ) 16 . , e ) 18 .
Output (English): b