Task: Question Answering
Input (English): Problem: if 2 ^ y = 4 ^ ( 5 x + 3 ) and 3 ^ ( x - 7 ) = 9 ^ y , what is the value of x + y ? 
Options: a ) - 10 , b ) - 5 , c ) - 4 , d ) 3 , e ) 7
Output (English): b