Question

Solve each system of equations by substitution
2y-6z=-30
-y-z=-1

Answer 1

2y-6z=-30---------(1)
-y-z=-1---------(2)

in equation (2)
-y-z=-1
-y=-1+z
-y=z-1
y=-(z-1)

y=1-z----------(3)

put equation (3) in equation (1)

2(1-z)-6z=-30
2-2z-6z=-30
2-8z=-30
-8z=-32

z=4

put z in equation (3)

y=1-4

y=-3

Solution is (-3,4)