Can some one show me how to use the Substitution method to solve the system of these equations.

Question

x + y = -4
x - y = 2

x + y = 10
y = x + 8

on the first set.
Solve for either x or y in either equation, then put that value into the other equation.

Example:
x + y = -4
x - y = 2

solve for x in the first:
x= -y-4
Put it in the second then..
-y-4 -y=2
-2y=6
y=-3
then solve for x..
x=-y-4=-1