Respuesta :

bcalle
  3x - 9y = -12
-(3x - 15y = -6) subtract the second equation from the first
         6y   = -6  divide both sides by 6
         y = -1
Plug -1 into either original equation and solve for x

3x -9(-1) = -12
3x + 9 = -12
3x = -21
x = -7
(-7,-1)