Use the point-slope formula:

y - y1 = m(x - x1)
where (x1,y1) = (3,8)
and m = 

y - 8 = (x - 3)

Multiply both sides by 9

9y - 72 = 8(x - 3)
9y - 72 = 8x - 24
-8x + 9y = 48

 8x - 9y = -48

That's the general form.

Or,

y - 8 = (x - 3)
y - 8 = x - 3·
y - 8 = x -   
    y = x -  + 8
    y = x -  + 
    y = x + 

That's the slope-intercept form.

Edwin