2x+2y=8 in function form step by step ?

You could get two different functions out of this:

2x + 2y = 8

1).  'y' as a function of 'x'

Subtract  2x  from each side:  2y  = -2x + 8

Divide each side by  2 :          y  =  -x + 4

2).  'x' as a function of 'y' :

Subtract  2y  from each side:    2x  =  -2y + 8

Divide each side by  2 :          x  =  -y + 4

Those two functions look the same, but that's just because the original
equation given in the problem was so symmetrical.  In general, they're
not the same function.