Question

solve the system by substitution
2x-y+z=-4
z=5
-2x+3y-z=-10

a)(-8,7,5)
b)(-8,-7,5)
c)(8,-7,5)
d)(-8,-7,-5)

Answer 1

you are given that z=5 from the beginning , so you
can go ahead and substitute this into the remaining
two equations.

Answer 2

2x-y+5=-4
-2x+3y-5=-10


2x - y = -9
-2x + 3y = -5

Answer 3

then add the two equations and that will help you solve for y.