Explanation:
x + 6y = 8 ........... ( ×2 ) ....... ( 1 )
2x + 4y = -8 ......... ( × 1 ) ....... ( 2 )
 2x + 12y = 16
 - - -
 2x + 4y = -8 
 +12y - ( +4y ) = 16 - 8
 12y - 4y = 8
 8y = 8
 divide both sides by the coefficient of y ( 8 )
 8y / 8 = 8 / 8
 y = 1
 substitute for x in equation ( 1 )
 x + 6y = 8
 x + 6 ( 1 ) = 8
 x + 6 = 8 
 x = 8 - 6
 x = 2 
 x = 2 , y = 1