Key point 1. When we talk about the distance between a point and a line it means the perpendicular distance.
With that in mind here we go.
We start with the line
So the slope of this line is
So the slope of the perpendicular line is
So the equation of the line is
Now we want to find the intersection of these two lines so we set them equal.
clearing the fractions we get
Now we can sub this into either equation of the line to get the y coordinate
Now we can use the pythagorean theorem to find the distance between the two lines.
Simplifing we get
This should get you started. Good luck.