Write the augmented matrix of the system and use it to solve the system.

{42x + 7y - 3z- 42w= -25
{12x + 5y - z - 12w= -1
{-12x + 5y - z -12w= 7
{84x + 14y -6z - 86w= -50

x=
y=
z=
w=