y=6-x, y=x+2

Well these would be two equation so:

y=6-x (1)
y=x+2 (2)

so,
substitute equation (1) y=6-x into equation (2)

therefore,
6-x=x+2
6-2=x+x
4=2x
4/2=x
2=x

for x=2, substitute x in equation (1)
y=6-2
y=4

x=2 , y=4