Question 830042
To use substitution we need to solve for x in one of the equations.
Let's take x-y=1
subtract y from each side
x = y + 1
The other equation is
x + y = -3
Substitute (y + 1) for x in this equation.
(y + 1) + y = -3
2y + 1 = -3
add -1 to each side
2y = -4
divide each side by 2
 y = -2
Now substitute -2 for y in x = y + 1
x = -2 + 1
x = -1