Respuesta :

4x + 3y = 54 (1)
3x + 9y = 108 (2)

Multiply (1) by (-3)
-12x - 9y = -162 
3x + 9y = 108
---------------------add
-9x  =  -54
   x = 6

plug x = 6 into (1) to find y
4(6) + 3y = 54
24 + 3y = 54
3y = 30
  y = 10

Answer
(6 , 10)

Hope it helps.