Line equation:
(y - yo) = m.(x - xo)
Where (xo, yo) is a point of this line and m his angular coeficient.
To a line be parallel to other their angular coeficient needs to be equal, in a line equation (y = ax + b) the angular coeficient is "a".
So, in y = 5x + 1, a = 5. So,
(y - yo) = 5.(x - xo)
Now, just put the point coordinates in xo and yo.
(y - 8) = 5.(x - 5)
y - 8 = 5x - 25
y = 5x - 25 + 8
y = 5x - 17
