Hi there
y = -x + 1
2x - y = 5
Let's use the substitution method as they asked :)
Substitute -x + 1 for y in 2x - y = 5
2x - (-x+1) = 5
2x + x - 1 = 5
3x - 1 = 5
3x = 5 + 1
3x = 6
x = 6/3
x = 2
Now we need to substitute 2 for x in y = -x + 1
y = -x + 1
y = -2 + 1
y = -1
Final solution : X = 2 and Y = -1
I hope you have a wonderful Christmas.