Question

2x-5y=13
4y+z=-8
x-y-z=-2

Answer 1

Despejando "x":
$2x - 5y=13$
$2x= 13+5y$
$x= (13+5y)/2$

Despejando "z":
$4y+z=-8$
$z= -8-4y$

Entonces, hallamos el valor de "y":
$x-y-z= -2$
$[(13+5y)/2]-y-(-8-4y)=-2$
$[(13+5y)/2]-y-+8+4y=-2$
$[(13+5y)/2]+8+3y=-2$
$(13+5y+16+6y) / 2 =-2$
$29+11y=-4$
$11y=-33$
$y=-3$

Obteniendo el valor de "x":
$x= (13+5y)/2$
$x= (13+5(-3))/2$
$x=-2/2$
$x=-1$

Obteniendo el valor de "z":
$z= -8-4y$
$z= -8-4(-3)$
$y=4$

Rpta:
x= -1 
y= -3
z= 4