Perpendicular Lines and the equation of a tangent

$A\,$ is the point $(0, 3)$

$B\,$ is the point $(4, 11)$

The equation of the straight line through $A\,$ and $B\,$ is $y = 2 x + 3$

a.

Write down the equation of another straight line parallel to $y = 2 x + 3$

[1]

b.

Write down the equation of another straight line that passes through the point $(0, 3)$

[1]

c.

Find the equation of the line perpendicular to $AB\,$ passing through $B$ .

[3]