What is the value of x + y + z when 6x + 5y - 2z = -4 and 4x + 5y + 12z = 54?

I'm really stuck on this problem. Can someone please help?

Thanks!!

Respuesta :

Using systems of equations I ended up getting these two equations:
x = 7z - 29
y = -8z-30.9

Plug in the variables into the equation x + y + z:
(7z - 29)-(8z -30.8)+ z
Add and the equation ends up equal to -59.8